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This '''glossary of computer science''' is a list of definitions of terms and concepts used in [[Computer science|computer science]], its sub-disciplines, and related fields, including terms relevant to [[Software|software]], [[Data science|data science]], and {{gli|computer programming}}.


==A==
{{glossary}}
{{term|[[Abstract data type|abstract data type]] (ADT)}}
{{defn|A [[Mathematical model|mathematical model]] for {{gli|data type|data types}} in which a data type is defined by its behavior ({{gli|semantics}}) from the point of view of a {{gli|user}} of the data, specifically in terms of possible values, possible operations on data of this type, and the behavior of these operations. This contrasts with {{gli|data structure|data structures}}, which are concrete representations of data from the point of view of an implementer rather than a user.}}

{{term|abstract method}}
{{defn|One with only a signature and no implementation body. It is often used to specify that a subclass must provide an implementation of the method. Abstract methods are used to specify {{gli|interface|interfaces}} in some computer languages.<ref>{{cite web|title=Abstract Methods and Classes|url=http://docs.oracle.com/javase/tutorial/java/IandI/abstract.html|website=oracle.com|publisher=Oracle Java Documentation|access-date=11 December 2014}}</ref>}}

{{term|abstraction}}
{{defn|no=1|In [[Software engineering|software engineering]] and {{gli|computer science}}, the process of removing physical, spatial, or temporal details<ref>{{Cite journal|last1=Colburn|first1=Timothy|last2=Shute|first2=Gary|date=2007-06-05|title=Abstraction in Computer Science|journal=Minds and Machines|language=en|volume=17|issue=2|pages=169–184|doi=10.1007/s11023-007-9061-7|s2cid=5927969|issn=0924-6495}}</ref> or {{gli|attribute|attributes}} in the study of objects or systems in order to more closely attend to other details of interest;<ref name="abstraction">{{Cite journal|last=Kramer|first=Jeff|date=2007-04-01|title=Is abstraction the key to computing?|journal=Communications of the ACM|volume=50|issue=4|pages=36–42|doi=10.1145/1232743.1232745|issn=0001-0782|citeseerx=10.1.1.120.6776|s2cid=12481509}}</ref> it is also very similar in nature to the process of [[Generalization|generalization]].}}
{{defn|no=2|The result of this process: an [[Philosophy:Abstract and concrete|abstract]] [[Philosophy:Concept|concept]]-[[Philosophy:Object|object]] created by keeping common features or attributes to various concrete objects or systems of study.<ref name="abstraction" />}}

{{term|[[Agent architecture|agent architecture]]}}
{{defn|A [[Blueprint|blueprint]] for {{gli|software agent|software agents}} and [[Intelligent control|intelligent control]] systems depicting the arrangement of components. The architectures implemented by [[Intelligent agent|intelligent agent]]s are referred to as [[Cognitive architecture|cognitive architecture]]s.<ref>[http://hri.cogs.indiana.edu/publications/aaai04ws.pdf Comparison of Agent Architectures] {{webarchive |url=https://web.archive.org/web/20080827222057/http://hri.cogs.indiana.edu/publications/aaai04ws.pdf |date=August 27, 2008 }}</ref>}}

{{term|[[Agent-based model|agent-based model]] (ABM)}}
{{defn|A class of {{gli|computational model|computational models}} for [[Computer simulation|simulating]] the actions and interactions of autonomous agents (both individual or collective entities such as organizations or groups) with a view to assessing their effects on the system as a whole. It combines elements of [[Game theory|game theory]], complex systems, [[Philosophy:Emergence|emergence]], [[Computational sociology|computational sociology]], [[Multi-agent system|multi-agent system]]s, and [[Evolutionary programming|evolutionary programming]]. [[Monte Carlo method]]s are used to introduce randomness.}}

{{term|[[Aggregate function|aggregate function]]}}
{{defn|In database management, a {{gli|subroutine|function}} in which the values of multiple rows are grouped together to form a single value of more significant meaning or measurement, such as a sum, count, or max.}}

{{term|[[Agile software development|agile software development]]}}
{{defn|An approach to [[Software development|software development]] under which requirements and solutions evolve through the collaborative effort of self-organizing and [[Social:Cross-functional team|cross-functional]] teams and their [[Social:Customer|customer(s)]]/[[End user|end user(s)]].<ref name="Collier 2011">{{cite book |title= Agile Analytics: A Value-Driven Approach to Business Intelligence and Data Warehousing |last=Collier|first=Ken W. |year=2011 |publisher= Pearson Education |isbn=9780321669544 | pages= 121 ff|quote=What is a self-organizing team?}}</ref> It advocates adaptive planning, evolutionary development, early delivery, and [[Continual improvement process|continual improvement]], and it encourages rapid and flexible response to change.<ref name="WhatIsAgile">{{cite web|url = http://www.agilealliance.org/the-alliance/what-is-agile/|title = What is Agile Software Development?|date = 8 June 2013|access-date = 4 April 2015|publisher = Agile Alliance}}</ref>}}

{{term|[[Algorithm|algorithm]]}}
{{defn|An unambiguous specification of how to solve a class of problems. Algorithms can perform [[Calculation|calculation]], [[Data processing|data processing]], and [[Automated reasoning|automated reasoning]] tasks. They are ubiquitous in computing technologies.}}

{{term|algorithm design}}
{{defn|A method or mathematical process for problem-solving and for engineering {{gli|algorithm|algorithms}}. The design of algorithms is part of many solution theories of operation research, such as [[Dynamic programming|dynamic programming]] and [[Divide and conquer algorithm|divide-and-conquer]]. Techniques for designing and implementing algorithm designs are also called algorithm design patterns,<ref>{{citation|url=http://ww3.algorithmdesign.net/ch00-front.html|title=Algorithm Design: Foundations, Analysis, and Internet Examples|last1=Goodrich|first1=Michael T.|last2=Tamassia|first2=Roberto|publisher=John Wiley & Sons, Inc.|year=2002|isbn=978-0-471-38365-9}}</ref> such as the template method pattern and decorator pattern.}}

{{term|[[Algorithmic efficiency|algorithmic efficiency]]}}
{{defn|A property of an {{gli|algorithm}} which relates to the number of [[Computational resource|computational resource]]s used by the algorithm. An algorithm must be [[Analysis of algorithms|analyzed]] to determine its resource usage, and the efficiency of an algorithm can be measured based on usage of different resources. Algorithmic efficiency can be thought of as analogous to engineering [[Finance:Productivity|productivity]] for a repeating or continuous process.}}

{{term|American Standard Code for Information Interchange (ASCII)}}
{{defn|A [[Character encoding|character encoding]] standard for electronic communications. ASCII codes represent text in computers, [[Engineering:Telecommunications equipment|telecommunications equipment]], and other devices. Most modern character-encoding schemes are based on ASCII, although they support many additional characters.}}

{{term|[[Application programming interface|application programming interface]] (API)}}
{{defn|A set of {{gli|subroutine}} definitions, communication protocols, and tools for building {{gli|software}}. In general terms, it is a set of clearly defined methods of communication among various components. A good API makes it easier to develop a {{gli|computer program}} by providing all the building blocks, which are then put together by the [[Programmer|programmer]].}}

{{term|application software}}
{{ghat|Also simply '''application''' or '''app'''.}}
{{defn|{{gli|software|Computer software}} designed to perform a group of coordinated functions, tasks, or activities for the benefit of the {{gli|user}}. Common examples of applications include [[Software:Word processor|word processor]]s, [[Engineering:Spreadsheet|spreadsheet]]s, [[Software:Accounting software|accounting application]]s, [[Software:Web browser|web browser]]s, [[Software:Media player|media player]]s, aeronautical [[Flight simulator|flight simulator]]s, [[Software:Console game|console game]]s, and [[Software:Raster graphics editor|photo editor]]s. This contrasts with {{gli|system software}}, which is mainly involved with managing the computer's most basic running operations, often without direct input from the user. The collective noun ''application software'' refers to all applications collectively.<ref>{{cite web |title=Application software |url=https://www.pcmag.com/encyclopedia/term/37919/application-program | work=PC Magazine |publisher=Ziff Davis}}</ref>}}

{{term|[[Array data structure|array data structure]]}}
{{ghat|Also simply '''array'''.}}
{{defn|A {{gli|data structure}} consisting of a collection of ''elements'' ({{gli|value|values}} or {{gli|variable|variables}}), each identified by at least one ''array index'' or ''key''. An array is stored such that the position of each element can be computed from its index [[Tuple|tuple]] by a mathematical formula.<ref>{{cite web|url=https://xlinux.nist.gov/dads/HTML/array.html|title=array|last=Black|first=Paul E.|date=13 November 2008|work=[[Dictionary of Algorithms and Data Structures]]|publisher=[[Organization:National Institute of Standards and Technology|National Institute of Standards and Technology]]|access-date=22 August 2010}}</ref><ref name="andres">{{cite arXiv |eprint=1008.2909 |author1=Bjoern Andres |author2=Ullrich Koethe |author3=Thorben Kroeger |author4=Hamprecht |title=Runtime-Flexible Multi-dimensional Arrays and Views for C++98 and C++0x |class=cs.DS |year=2010}}</ref><ref name="garcia">{{Cite journal|last1=Garcia|first1=Ronald |first2=Andrew |last2=Lumsdaine|year=2005|title=MultiArray: a C++ library for generic programming with arrays|journal=Software: Practice and Experience|volume=35|issue=2|pages=159–188|issn=0038-0644|doi=10.1002/spe.630|s2cid=10890293 }}</ref> The simplest type of data structure is a linear array, also called a one-dimensional array.}}

{{term|[[Software:Artifact (software development)|artifact]]}}
{{defn|One of many kinds of tangible by-products produced during the development of {{gli|software}}. Some artifacts (e.g. [[Use case|use case]]s, [[Class diagram|class diagram]]s, and other [[Unified Modeling Language]] (UML) models, requirements, and design documents) help describe the function, architecture, and design of software. Other artifacts are concerned with the process of development itself—such as project plans, business cases, and risk assessments.}}

{{term|[[Artificial intelligence|artificial intelligence]] (AI)}}
{{ghat|Also '''machine intelligence'''.}}
{{defn|[[Philosophy:Intelligence|Intelligence]] demonstrated by machines, in contrast to the natural intelligence displayed by humans and other animals. In {{gli|computer science}}, AI research is defined as the study of "[[Intelligent agent|intelligent agent]]s": devices capable of perceiving their environment and taking actions that maximize the chance of successfully achieving their goals.<ref name="Definition of AI">
Definition of AI as the study of intelligent agents:
* {{Harvnb|Poole|Mackworth|Goebel|1998|loc=[http://people.cs.ubc.ca/~poole/ci/ch1.pdf p. 1]}}, which provides the version that is used in this article. Note that they use the term "computational intelligence" as a synonym for artificial intelligence.
* {{Harvtxt|Russell|Norvig|2003}} (who prefer the term "rational agent") and write "The whole-agent view is now widely accepted in the field" {{Harv|Russell|Norvig|2003|p=55}}.
* {{Harvnb|Nilsson|1998}}
<!--These textbooks are the most widely used in academic AI.-->
* {{Harvnb|Legg|Hutter|2007}}.
</ref> Colloquially, the term "artificial intelligence" is applied when a machine mimics "cognitive" functions that humans associate with other human minds, such as "learning" and "problem solving".{{sfn|Russell|Norvig|2009|p=2}}}}

{{term|[[ASCII]]}}
{{defn|See ''{{gli|American Standard Code for Information Interchange}}''.}}

{{term|[[Software:Assertion (software development)|assertion]]}}
{{defn|In {{gli|computer programming}}, a {{gli|statement}} that a [[Predicate (mathematical logic)|predicate]] ([[Boolean-valued function]], i.e. a true–false {{gli|expression}}) is always true at that point in code execution. It can help a programmer read the code, help a {{gli|compiler}} compile it, or help the program detect its own defects. For the latter, some programs check assertions by actually evaluating the predicate as they run and if it is not in fact true – an assertion failure – the program considers itself to be broken and typically deliberately {{gli|crash|crashes}} or throws an assertion failure [[Exception handling|exception]].}}

{{term|[[Associative array|associative array]]}}
{{defn|An associative array, map, symbol table, or dictionary is an [[Abstract data type|abstract data type]] composed of a [[Collection (abstract data type)|collection]] of [[Attribute–value pair|(key, value) pairs]], such that each possible key appears at most once in the collection.

Operations associated with this data type allow:<ref name="gt">{{citation|contribution=9.1 The Map Abstract Data Type|title=Data Structures & Algorithms in Java|last1=Goodrich|first1=Michael T.|last2=Tamassia|first2=Roberto|publisher=Wiley|edition=4th|year=2006|pages=368–371}}</ref><ref name="ms">{{citation|contribution=4 Hash Tables and Associative Arrays|title=Algorithms and Data Structures: The Basic Toolbox|first1=Kurt|last1=Mehlhorn|author1-link=Kurt Mehlhorn|first2=Peter|last2=Sanders|author2-link=Peter Sanders (computer scientist)|publisher=Springer|year=2008|pages=81–98 |url=http://people.mpi-inf.mpg.de/~mehlhorn/ftp/Toolbox/HashTables.pdf}}</ref>

* the addition of a pair to the collection
* the removal of a pair from the collection
* the modification of an existing pair
* the lookup of a value associated with a particular key}}

{{term|[[Automata theory|automata theory]]}}
{{defn|The study of [[Abstract machine|abstract machine]]s and [[Engineering:Automaton|automata]], as well as the [[Computational problem|computational problem]]s that can be solved using them. It is a theory in {{gli|theoretical computer science}} and [[Discrete mathematics|discrete mathematics]] (a subject of study in both [[Mathematics|mathematics]] and {{gli|computer science}}).}}

{{term|[[Automated reasoning|automated reasoning]]}}
{{defn|An area of {{gli|computer science}} and [[Mathematical logic|mathematical logic]] dedicated to understanding different aspects of reasoning. The study of automated reasoning helps produce computer programs that allow computers to reason completely, or nearly completely, automatically. Although automated reasoning is considered a sub-field of {{gli|artificial intelligence}}, it also has connections with {{gli|theoretical computer science}}, and even [[Philosophy:Philosophy|philosophy]].}}
{{glossaryend}}

==B==
{{glossary}}
{{term|[[Bandwidth (computing)|bandwidth]]}}
{{defn|The maximum rate of data transfer across a given path. Bandwidth may be characterized as ''network bandwidth'',<ref>[[Biography:Douglas Comer|Douglas Comer]], [https://books.google.com/books?id=tm-evHmOs3oC&dq=%22network+bandwidth%22+%22computer+networks%22&pg=PA99 Computer Networks and Internets], page 99 ff, Prentice Hall 2008.</ref> ''data bandwidth'',<ref>Fred Halsall, [https://books.google.com/books?id=HrXbAAAAMAAJ&q=%100data+bandwidth%100+Introduction to data+communications and computer networks], page 108, Addison-Wesley, 1985.</ref> or ''digital bandwidth''.<ref>[https://books.google.com/books?id=7gqsZmr5HJcC&q=+0digital+bandwidth+0+%22 Cisco Networking Academy Program: CCNA 1 and 2 companion guide, Volym 1–2], Cisco Academy 2003</ref><ref>Behrouz A. Forouzan, ''Data communications and networking'', McGraw-Hill, 2007</ref>}}

{{term|[[Bayesian programming]]}}
{{defn|A formalism and a methodology for having a technique to specify [[Probability distribution|probabilistic models]] and solve problems when less than the necessary information is available.}}

{{term|[[Benchmark (computing)|benchmark]]}}
{{defn|The act of running a {{gli|computer program}}, a set of programs, or other operations, in order to assess the relative performance of an object, normally by running a number of standard tests and trials against it.<ref>{{Cite journal| doi = 10.1145/5666.5673| issn = 0001-0782| volume = 29| issue = 3| pages = 218–221| last1 = Fleming| first1 = Philip J.| last2 = Wallace| first2 = John J.| title = How not to lie with statistics: the correct way to summarize benchmark results| journal = Communications of the ACM| date = 1986-03-01| s2cid = 1047380| doi-access = free}}</ref> The term ''benchmark'' is also commonly utilized for the purposes of elaborately designed benchmarking programs themselves.}}

{{term|[[Best, worst and average case|best, worst and average case]]}}
{{defn|Expressions of what the {{gli|resource}} usage is ''at least'', ''at most'', and ''on average'', respectively, for a given {{gli|algorithm}}. Usually the resource being considered is running time, i.e. [[Time complexity|time complexity]], but it could also be memory or some other resource. ''Best case'' is the function which performs the minimum number of steps on input data of ''n'' elements; ''worst case'' is the function which performs the maximum number of steps on input data of size ''n''; ''average case'' is the function which performs an average number of steps on input data of ''n'' elements.}}

{{term|[[Big data|big data]]}}
{{defn|A term used to refer to [[Data set|data set]]s that are too large or complex for traditional [[Data processing|data-processing]] {{gli|application software}} to adequately deal with. Data with many cases (rows) offer greater statistical power, while data with higher complexity (more attributes or columns) may lead to a higher [[False discovery rate|false discovery rate]].<ref>{{Cite journal|last=Breur|first=Tom|date=July 2016|title=Statistical Power Analysis and the contemporary "crisis" in social sciences|journal=Journal of Marketing Analytics|language=en|volume=4|issue=2–3|pages=61–65|doi=10.1057/s41270-016-0001-3|issn=2050-3318|doi-access=free}}</ref>}}

{{term|[[Big O notation|big O notation]]}}
{{defn|A mathematical notation that describes the [[Asymptotic analysis|limiting behavior]] of a [[Function (mathematics)|function]] when the argument tends towards a particular value or infinity. It is a member of a family of notations invented by [[Biography:Paul Gustav Heinrich Bachmann|Paul Bachmann]],<ref name=Bachmann>{{cite book |first=Paul |last=Bachmann |title=Analytische Zahlentheorie |trans-title=Analytic Number Theory |language=de |volume=2 |location=Leipzig |publisher=Teubner |date=1894 |url=https://archive.org/stream/dieanalytischeza00bachuoft#page/402/mode/2up}}</ref> [[Biography:Edmund Landau|Edmund Landau]],<ref name=Landau>{{cite book |first=Edmund |last=Landau |author-link=Edmund Landau |title=Handbuch der Lehre von der Verteilung der Primzahlen |publisher=B. G. Teubner |date=1909 |location=Leipzig |trans-title=Handbook on the theory of the distribution of the primes |language=de |page=883 | url=https://archive.org/details/handbuchderlehre01landuoft}}</ref> and others, collectively called ''Bachmann–Landau notation'' or ''asymptotic notation''.}}

{{term|[[Binary number|binary number]]}}
{{defn|In mathematics and [[Engineering:Digital electronics|digital electronics]], a number expressed in the base-2 numeral system or binary numeral system, which uses only two symbols: typically 0 (zero) and 1 (one).}}

{{term|[[Binary search algorithm|binary search algorithm]]}}
{{ghat|Also simply '''binary search''', '''half-interval search''',<ref name="Williams1976">{{cite conference|last1=Williams, Jr.|first1=Louis F.|title=A modification to the half-interval search (binary search) method|conference=Proceedings of the 14th ACM Southeast Conference|date=22 April 1976|pages=95–101|doi=10.1145/503561.503582|url=https://dl.acm.org/citation.cfm?doid=503561.503582|publisher=ACM|access-date=29 June 2018|archive-url=https://web.archive.org/web/20170312215255/http://dl.acm.org/citation.cfm?doid=503561.503582|archive-date=12 March 2017|url-status=live|df=dmy-all|doi-access=free}}</ref> '''logarithmic search''',{{Sfn|Knuth|1998|loc=§6.2.1 ("Searching an ordered table"), subsection "Binary search"}} or '''binary chop'''.{{Sfn|Butterfield|Ngondi|2016|p=46}}}}
{{defn|A {{gli|search algorithm}} that finds the position of a target value within a [[Sorted array|sorted array]].<ref>{{Introduction to Algorithms|edition=3|pages=39}}</ref>}}

{{term|[[Binary tree|binary tree]]}}
{{defn|A [[Tree structure|tree]] {{gli|data structure}} in which each node has at most two children, which are referred to as the ''{{visible anchor|left child}}'' and the ''{{visible anchor|right child}}''. A [[Recursive definition|recursive definition]] using just [[Set theory|set theory]] notions is that a (non-empty) binary tree is a [[Tuple|tuple]] (''L'', ''S'', ''R''), where ''L'' and ''R'' are binary trees or the [[Empty set|empty set]] and ''S'' is a singleton set.<ref name="GarnierTaylor2009">{{cite book|author1=Rowan Garnier|author2=John Taylor|title=Discrete Mathematics: Proofs, Structures and Applications, Third Edition|url=https://books.google.com/books?id=WnkZSSc4IkoC&pg=PA620|year=2009|publisher=CRC Press|isbn=978-1-4398-1280-8|page=620}}</ref> Some authors allow the binary tree to be the empty set as well.<ref name="Skiena2009">{{cite book|author=Steven S Skiena|title=The Algorithm Design Manual|url=https://books.google.com/books?id=7XUSn0IKQEgC&pg=PA77|year=2009|publisher=Springer Science & Business Media|isbn=978-1-84800-070-4|page=77}}</ref>}}

{{term|[[Biology:Bioinformatics|bioinformatics]]}}
{{defn|An interdisciplinary field that combines [[Biology:Biology|biology]], {{gli|computer science}}, [[Information engineering (field)|information engineering]], [[Mathematics|mathematics]], and [[Statistics|statistics]] to develop methods and software tools for analyzing and interpreting biological data. Bioinformatics is widely used for ''[[Biology:In silico|in silico]]'' analyses of biological queries using mathematical and statistical techniques.}}

{{term|[[Bit|bit]]}}
{{defn|A [[Units of information|basic unit of information]] used in {{gli|computing}} and digital communications; a portmanteau of ''binary digit''. A {{gli|binary number|binary}} digit can have one of two possible {{gli|value|values}}, and may be physically represented with a two-state device. These state values are most commonly represented as either a {{gaps|0|or|1}}.<ref name="Mackenzie_1980">{{cite book |title=Coded Character Sets, History and Development |work=The Systems Programming Series |author-last=Mackenzie |author-first=Charles E. |year=1980 |edition=1 |publisher=Addison-Wesley Publishing Company, Inc. |isbn=978-0-201-14460-4 |lccn=77-90165 |page=x |url=https://books.google.com/books?id=6-tQAAAAMAAJ |access-date=2016-05-22 |url-status=live |archive-url=https://web.archive.org/web/20161118230039/https://books.google.com/books?id=6-tQAAAAMAAJ |archive-date=18 November 2016 |df=dmy-all }} [https://web.archive.org/web/20160526172151/https://textfiles.meulie.net/bitsaved/Books/Mackenzie_CodedCharSets.pdf]</ref>}}

{{term|[[Bit rate|bit rate]] (''R'')}}

{{ghat|Also '''bitrate'''.}}

{{defn|In telecommunications and {{gli|computing}}, the number of {{gli|bit|bits}} that are conveyed or processed per unit of time.<ref>{{cite book |url = https://books.google.com/books?id=-kNn_p6WA38C&q=bit+%22rate+R%22&pg=PA21 |title=Data Communications and Computer Networks | first =Prakash C | last = Gupta |publisher=PHI Learning |year= 2006 |access-date=10 July 2011|isbn=9788120328464 }}</ref>}}

{{term|[[Blacklist (computing)|blacklist]]}}
{{ghat|Also '''block list'''.}}
{{defn|In {{gli|computing}}, a basic [[Access control|access control]] mechanism that allows through all elements (email addresses, users, passwords, URLs, [[IP address]]es, [[Domain name|domain name]]s, file hashes, etc.), except those explicitly mentioned in a list of prohibited elements. Those items on the list are denied access. The opposite is a {{gli|whitelist}}, which means only items on the list are allowed through whatever gate is being used while all other elements are blocked. A [[Software:Greylisting (email)|greylist]] contains items that are temporarily blocked (or temporarily allowed) until an additional step is performed.}}

{{term|BMP file format}}
{{ghat|Also '''bitmap image file''', '''device independent bitmap (DIB) file format''', or simply '''bitmap'''.}}
{{defn|A [[Raster graphics|raster graphics]] [[Image file format|image file format]] used to store [[Bitmap|bitmap]] digital images independently of the [[Engineering:Display device|display device]] (such as a graphics adapter), used especially on [[Software:Microsoft Windows|Microsoft Windows]]<ref name="bmp">{{cite book|title=Encyclopedia of Graphics File Formats|edition=Second|date=April 1996|author=James D. Murray|author2=William vanRyper|isbn=978-1-56592-161-0|publisher=O'Reilly|at=bmp|url=https://archive.org/details/mac_Graphics_File_Formats_Second_Edition_1996|access-date=2014-03-07}}</ref> and OS/2<ref name="os2bmp">{{cite book|title=Encyclopedia of Graphics File Formats|edition=Second|date=April 1996|author=James D. Murray|author2=William vanRyper|isbn=978-1-56592-161-0|publisher=O'Reilly|at=os2bmp|url=https://archive.org/details/mac_Graphics_File_Formats_Second_Edition_1996|access-date=2014-03-07}}</ref> operating systems.}}

{{term|[[Boolean data type]]}}
{{defn|A [[Data type|data type]] that has one of two possible values (usually denoted ''true'' and ''false''), intended to represent the two [[Philosophy:Truth value|truth value]]s of [[Logic|logic]] and [[Boolean algebra]]. It is named after [[Biography:George Boole|George Boole]], who first defined an algebraic system of logic in the mid-19th century. The Boolean data type is primarily associated with [[Conditional (computer programming)|conditional]] statements, which allow different actions by changing [[Control flow|control flow]] depending on whether a programmer-specified Boolean ''condition'' evaluates to true or false. It is a special case of a more general ''logical data type'' (see [[Probabilistic logic|probabilistic logic]])—i.e. logic need not always be Boolean.}}

{{term|[[Boolean expression]]}}
{{defn|An {{gli|expression}} used in a {{gli|programming language}} that returns a Boolean value when evaluated, that is one of ''true'' or ''false''. A Boolean expression may be composed of a combination of the Boolean constants ''true'' or ''false'', [[Boolean data type|Boolean-typed]] variables, Boolean-valued operators, and [[Boolean-valued function]]s.<ref>{{citation
 | contribution = Chapter 2. Boolean Expressions
 | isbn = 9780387941158
 | page = 25ff
 | publisher = Springer
 | series = Monographs in Computer Science
 | title = A Logical Approach to Discrete Math
 | url = https://books.google.com/books?id=ZWTDQ6H6gsUC&pg=PA25
 | year = 1993}}</ref>}}

{{term|[[Boolean algebra]]}}
{{defn|In mathematics and [[Mathematical logic|mathematical logic]], the branch of [[Algebra|algebra]] in which the values of the variables are the [[Philosophy:Truth value|truth value]]s ''true'' and ''false'', usually denoted 1 and 0, respectively. Contrary to [[Elementary algebra|elementary algebra]], where the values of the variables are numbers and the prime operations are addition and multiplication, the main operations of Boolean algebra are the [[Logical conjunction|conjunction]] ''and'' (denoted as ∧), the [[Logical disjunction|disjunction]] ''or'' (denoted as ∨), and the [[Negation|negation]] ''not'' (denoted as ¬). It is thus a formalism for describing logical relations in the same way that elementary algebra describes numeric relations.}}

{{term|[[Byte|byte]]}}
{{defn|A [[Units of information|unit of digital information]] that most commonly consists of eight {{gli|bit|bits}}, representing a {{gli|binary number}}. Historically, the byte was the number of bits used to encode a single [[Character (computing)|character]] of text in a computer<ref name="Buchholz_1962">{{anchor|Buchholz-1962}}{{citation |title=Planning a Computer System – Project Stretch |author-first1=Gerrit Anne |author-last1=Blaauw |author-first2=Frederick Phillips |author-last2=Brooks, Jr. |author-link2=Frederick Phillips Brooks, Jr. |author-first3=Werner |author-last3=Buchholz |author-link3=Werner Buchholz |editor-first=Werner |editor-last=Buchholz |publisher=McGraw-Hill Book Company, Inc. / The Maple Press Company, York, PA. |lccn=61-10466 |year=1962 |chapter=4: Natural Data Units |pages=39–40 |chapter-url=http://archive.computerhistory.org/resources/text/IBM/Stretch/pdfs/Buchholz_102636426.pdf |access-date=2017-04-03 |url-status=live |archive-url=https://web.archive.org/web/20170403014651/http://archive.computerhistory.org/resources/text/IBM/Stretch/pdfs/Buchholz_102636426.pdf |archive-date=2017-04-03 |quote=[…] Terms used here to describe the structure imposed by the machine design, in addition to ''[[Bit|bit]]'', are listed below.<br />''Byte'' denotes a group of bits used to encode a character, or the number of bits transmitted in parallel to and from input-output units. A term other than ''[[Character (computing)|character]]'' is used here because a given character may be represented in different applications by more than one code, and different codes may use different numbers of bits (i.e., different byte sizes). In input-output transmission the grouping of bits may be completely arbitrary and have no relation to actual characters. (The term is coined from ''bite'', but respelled to avoid accidental mutation to ''bit''.)<br />A ''word'' consists of the number of data bits transmitted in parallel from or to memory in one memory cycle. Word size is thus defined as a structural property of the memory. (The term ''[[Catena (unit)|catena]]'' was coined for this purpose by the designers of the [[Company:Groupe Bull|Bull]] {{ill|Bull Gamma 60{{!}}GAMMA 60|fr|Gamma 60}} computer.)<br />''[[Block (data storage)|Block]]'' refers to the number of words transmitted to or from an input-output unit in response to a single input-output instruction. Block size is a structural property of an input-output unit; it may have been fixed by the design or left to be varied by the program. […]}}</ref><ref name="Bemer_1959">{{citation |author-first=Robert William |author-last=Bemer |author-link=Robert William Bemer |title=A proposal for a generalized card code of 256 characters |journal=[[Communications of the ACM]] |volume=2 |number=9 |pages=19–23 |year=1959 |doi=10.1145/368424.368435|s2cid=36115735 |doi-access=free }}</ref> and for this reason it is the smallest [[Address space|addressable]] unit of {{gli|memory}} in many {{gli|computer architecture|computer architectures}}.}}

{{term|[[Booting|booting]]}}
{{defn|The procedures implemented in starting up a [[Computer|computer]] or [[Computer appliance|computer appliance]] until it can be used. It can be initiated by hardware such as a button press or by a software command. After the power is switched on, the computer is relatively dumb and can read only part of its storage called {{gli|read-only memory}}. There, a small program is stored called [[Firmware|firmware]]. It does [[Power-on self-test|power-on self-test]]s and, most importantly, allows access to other types of memory like a hard disk and main memory. The firmware loads bigger [[Computer program|program]]s into the computer's [[Random-access memory|main memory]] and runs it.}}
{{glossaryend}}

==C==
{{glossary}}
{{term|[[Callback (computer programming)|callback]]}}
{{ghat|Also a '''call-after function'''.<ref>{{cite web|url=https://stackoverflow.com/a/7549753/653708|title=What is a callback function?|website=Stack Overflow|access-date=2018-05-16}}</ref>}}
{{defn|Any executable code that is passed as an {{gli|argument}} to other code that is expected to "call back" (execute) the argument at a given time. This execution may be immediate, as in a ''synchronous callback'', or it might happen at a later time, as in an ''asynchronous callback''.}}

{{term|[[Central processing unit|central processing unit]] (CPU)}}
{{defn|The electronic circuitry within a {{gli|computer}} that carries out the {{gli|instruction|instructions}} of a {{gli|computer program}} by performing the basic arithmetic, logic, controlling, and {{gli|input/output}} (I/O) operations specified by the instructions. The computer industry has used the term "central processing unit" at least since the early 1960s.<ref name="weik1961">{{cite report | author = Weik, Martin H. | title = A Third Survey of Domestic Electronic Digital Computing Systems | publisher = Ballistic Research Laboratory | url = http://ed-thelen.org/comp-hist/BRL61.html | year = 1961 }}</ref> Traditionally, the term "CPU" refers to a ''processor'', more specifically to its processing unit and {{gli|control unit}} (CU), distinguishing these core elements of a computer from external components such as main memory and I/O circuitry.<ref name="kuck">{{cite book|last1= Kuck|first1= David|title= Computers and Computations, Vol 1|date= 1978|publisher= John Wiley & Sons, Inc.|isbn= 978-0471027164|page= 12}}</ref>}}

{{term|[[Character (computing)|character]]}}
{{defn|A unit of information that roughly corresponds to a [[Social:Grapheme|grapheme]], grapheme-like unit, or symbol, such as in an [[Social:Alphabet|alphabet]] or syllabary in the written form of a [[Philosophy:Natural language|natural language]].<ref>{{cite web|url=http://www.merriam-webster.com/dictionary/character|title=Definition of CHARACTER|website=www.merriam-webster.com|access-date=1 April 2018}}</ref>}}

{{term|[[Cipher|cipher]]}}
{{ghat|Also '''cypher'''.}}
{{defn|In {{gli|cryptography}}, an {{gli|algorithm}} for performing [[Encryption|encryption]] or decryption&mdash;a series of well-defined steps that can be followed as a {{gli|procedure}}.}}

{{term|class}}
{{defn|In {{gli|object-oriented programming}}, an extensible program-code-template for creating objects, providing initial values for state ([[Member variable|member variable]]s) and implementations of behavior (member functions or methods).{{sfn|Gamma|Helm|Johnson|Vlissides|1995| p=14}}{{sfn|Bruce|2002|loc=2.1 Objects, classes, and object types, {{Google books|9NGWq3K1RwUC|Objects, classes, and object types|page=18|plainurl=yes}}}} In many languages, the class name is used as the name for the class (the template itself), the name for the default [[Constructor (object-oriented programming)|constructor]] of the class (a {{gli|subroutine}} that creates objects), and as the [[Data type|type]] of objects generated by [[Instance (computer science)|instantiating]] the class; these distinct concepts are easily conflated.{{sfn|Bruce|2002|loc=2.1 Objects, classes, and object types, {{Google books|9NGWq3K1RwUC|Objects, classes, and object types|page=18|plainurl=yes}}}}}}

{{term|[[Class-based programming|class-based programming]]}}
{{ghat|Also '''class-orientation'''.}}
{{defn|A style of {{gli|object-oriented programming}} (OOP) in which inheritance occurs via defining "{{gli|class|classes}}" of {{gli|object|objects}}, instead of via the objects alone (compare [[Prototype-based programming|prototype-based programming]]).}}

{{term|[[Client (computing)|client]]}}
{{defn|A piece of [[Computer hardware|computer hardware]] or {{gli|software}} that accesses a service made available by a [[Server (computing)|server]]. The server is often (but not always) on another computer system, in which case the client accesses the service by way of a [[Computer network|network]].<ref>Sadoski, Darleen. 
''Client/Server Software Architectures – An Overview'', Software Technology Roadmap, 1997-08-02. Retrieved on 2008-09-16.</ref> The term applies to the role that programs or devices play in the [[Client–server model|client–server model]].}}

{{term|[[Cleanroom software engineering|cleanroom software engineering]]}}
{{defn|A [[Software development process|software development process]] intended to produce software with a certifiable level of [[Reliability engineering|reliability]]. The cleanroom process was originally developed by [[Biography:Harlan Mills|Harlan Mills]] and several of his colleagues including Alan Hevner at [[Company:IBM|IBM]].<ref>{{cite journal|last=Mills|first=H.|author2=M. Dyer |author3=R. Linger|title=Cleanroom Software Engineering|journal=IEEE Software|volume=4|issue=5|date=September 1987|pages=19&ndash;25|doi=10.1109/MS.1987.231413|citeseerx=10.1.1.467.2435|s2cid=383170}}</ref> The focus of the cleanroom process is on defect prevention, rather than defect removal.}}

{{term|[[Closure (computer programming)|closure]]}}
{{ghat|Also '''lexical closure''' or '''function closure'''.}}
{{defn|A technique for implementing lexically scoped [[Name binding|name binding]] in a language with [[First-class function|first-class function]]s. [[Operational semantics|Operationally]], a closure is a [[Record (computer science)|record]] storing a function{{efn|The function may be stored as a [[Reference (computer science)|reference]] to a function, such as a [[Function pointer|function pointer]].}} together with an environment.<ref>Sussman and Steele. "Scheme: An interpreter for extended lambda calculus". "... a data structure containing a lambda expression, and an environment to be used when that lambda expression is applied to arguments." (Wikisource)</ref>}}

{{term|[[Cloud computing|cloud computing]]}}
{{defn|Shared pools of configurable computer [[System resource|system resource]]s and higher-level services that can be rapidly provisioned with minimal management effort, often over the [[Internet]].  Cloud computing relies on sharing of resources to achieve coherence and [[Finance:Economies of scale|economies of scale]], similar to a [[Finance:Public utility|public utility]].}}

{{term|[[Library (computing)|code library]]}}
{{defn|A collection of [[Non-volatile memory|non-volatile resources]] used by {{gli|computer program|computer programs}}, often for [[Software development|software development]]. These may include configuration data, documentation, help data, message templates, [[Code reuse|pre-written code]] and {{gli|subroutine|subroutines}}, {{gli|class|classes}}, {{gli|value|values}} or {{gli|data type|type}} specifications. In IBM's OS/360 and its successors they are referred to as partitioned data sets.}}

{{term|[[Computer programming|coding]]}}
{{defn|Computer programming is the process of designing and building an {{gli|executable}} {{gli|computer program}} for accomplishing a specific {{gli|computing}} task. Programming involves tasks such as analysis, generating {{gli|algorithm|algorithms}}, profiling algorithms' accuracy and resource consumption, and the implementation of algorithms in a chosen {{gli|programming language}} (commonly referred to as '''coding'''<ref name="tumblr2014">{{cite web|url=http://yearofcodes.tumblr.com/what-is-coding|title=What is coding|author=Shaun Bebbington|year=2014|access-date=2014-03-03}}</ref><ref name="tumblr1">{{cite web|url=http://yearofcodes.tumblr.com/what-is-programming|title=What is programming|author=Shaun Bebbington|year=2014|access-date=2014-03-03}}</ref>). The {{gli|source code}} of a program is written in one or more programming languages. The purpose of programming is to find a sequence of instructions that will automate the performance of a task for solving a given problem. The process of programming thus often requires expertise in several different subjects, including knowledge of the {{gli|domain|application domain}}, specialized algorithms, and formal [[Logic|logic]].}}

{{term|[[Coding theory|coding theory]]}}
{{defn|The study of the properties of [[Code|code]]s and their respective fitness for specific applications. Codes are used for {{gli|data compression}}, {{gli|cryptography}}, [[Error detection and correction|error detection and correction]], [[Data transmission|data transmission]] and [[Data storage|data storage]]. Codes are studied by various scientific disciplines—such as [[Information theory|information theory]], [[Electrical engineering|electrical engineering]], [[Mathematics|mathematics]], [[Social:Linguistics|linguistics]], and {{gli|computer science}}—for the purpose of designing efficient and reliable data transmission methods. This typically involves the removal of redundancy and the correction or detection of errors in the transmitted data.}}

{{term|[[Cognitive science|cognitive science]]}}
{{defn|The interdisciplinary, [[Science|scientific]] study of the [[Philosophy:Mind|mind]] and its processes.<ref>Cognitive science is an interdisciplinary field of researchers from Linguistics, psychology, neuroscience, philosophy, computer science, and anthropology that seek to understand the mind. [http://www.aft.org/newspubs/periodicals/ae/summer2002/willingham.cfm How We Learn: Ask the Cognitive Scientist]</ref> It examines the nature, the tasks, and the functions of [[Cognition|cognition]] (in a broad sense). Cognitive scientists study intelligence and behavior, with a focus on how nervous systems represent, process, and transform [[Information|information]]. Mental faculties of concern to cognitive scientists include language, perception, memory, attention, reasoning, and emotion; to understand these faculties, cognitive scientists borrow from fields such as linguistics, psychology, [[Artificial intelligence|artificial intelligence]], [[Philosophy:Philosophy of mind|philosophy]], [[Biology:Neuroscience|neuroscience]], and anthropology.<ref name="stanford1">Thagard, Paul, [http://plato.stanford.edu/archives/fall2008/entries/cognitive-science/ Cognitive Science], ''The Stanford Encyclopedia of Philosophy'' (Fall 2008 Edition), [[Biography:Edward N. Zalta|Edward N. Zalta]] (ed.).</ref>}}

{{term|[[Collection (abstract data type)|collection]]}}
{{defn|A collection or container is a grouping of some variable number of data items (possibly zero) that have some shared significance to the problem being solved and need to be operated upon together in some controlled fashion.  Generally, the data items will be of the same type or, in languages supporting inheritance, derived from some common ancestor type. A collection is a concept applicable to [[Abstract data type|abstract data type]]s, and does not prescribe a specific implementation as a concrete [[Data structure|data structure]], though often there is a conventional choice (see [[Container (type theory)|Container]] for [[Type theory|type theory]] discussion).}}

{{term|[[Comma-separated values|comma-separated values]] (CSV)}}
{{defn|A delimited [[Text file|text file]] that uses a comma to separate values. A CSV file stores [[Table (information)|tabular]] data (numbers and text) in [[Plain text|plain text]].  Each line of the file is a data {{gli|record}}.  Each record consists of one or more {{gli|field|fields}}, separated by commas. The use of the comma as a field separator is the source of the name for this [[File format|file format]].}}

{{term|[[Compiler|compiler]]}}

{{term|[[Computability theory|computability theory]]}}
{{defn|also known as '''recursion theory''', is a branch of [[Mathematical logic|mathematical logic]], of {{gli|computer science}}, and of the [[Theory of computation|theory of computation]] that originated in the 1930s with the study of [[Computable function|computable function]]s and [[Turing degree]]s. The field has since expanded to include the study of generalized computability and definability. In these areas, recursion theory overlaps with [[Proof theory|proof theory]] and [[Effective descriptive set theory|effective descriptive set theory]].}}

{{term|[[Computation|computation]]}}
{{defn|Any type of calculation<ref>[http://www.merriam-webster.com/dictionary/computation Computation] from the Free Merriam-Webster Dictionary</ref><ref>{{cite web|title=Computation: Definition and Synonyms from Answers.com|url=http://www.answers.com:80/topic/computation|website=Answers.com|access-date=26 April 2017|archive-url=https://web.archive.org/web/20090222005439/http://www.answers.com/topic/computation|archive-date=22 February 2009|url-status=dead}}</ref> that includes both arithmetical and non-arithmetical steps and follows a well-defined model, e.g. an {{gli|algorithm}}. The study of computation is paramount to the discipline of {{gli|computer science}}.}}

{{term|[[Biology:Computational biology|computational biology]]}}
{{defn|Involves the development and application of data-analytical and theoretical methods, mathematical modelling and computational simulation techniques to the study of biological, ecological, behavioural, and social systems.<ref>"NIH working definition of bioinformatics and computational biology" (PDF). Biomedical Information Science and Technology Initiative. 17 July 2000. Archived from the original (PDF) on 5 September 2012. Retrieved 18 August 2012.</ref> The field is broadly defined and includes foundations in [[Biology:Biology|biology]], [[Applied mathematics|applied mathematics]], [[Statistics|statistics]], [[Biology:Biochemistry|biochemistry]], [[Chemistry:Chemistry|chemistry]], [[Physics:Biophysics|biophysics]], [[Biology:Molecular biology|molecular biology]], [[Biology:Genetics|genetics]], [[Biology:Genomics|genomics]], [[Computer science|computer science]], and [[Biology:Evolution|evolution]].<ref>"About the CCMB". Center for Computational Molecular Biology. Retrieved 18 August 2012.</ref>  Computational biology is different from [[Biology:Biological computing|biological computing]], which is a subfield of [[Computer science|computer science]] and [[Computer engineering|computer engineering]] using bioengineering and [[Biology:Biology|biology]] to build [[Computer|computer]]s.}}

{{term|[[Chemistry:Computational chemistry|computational chemistry]]}}
{{defn|A branch of [[Chemistry:Chemistry|chemistry]] that uses [[Computer simulation|computer simulation]] to assist in solving chemical problems. It uses methods of [[Chemistry:Theoretical chemistry|theoretical chemistry]], incorporated into efficient {{gli|computer program|computer programs}}, to calculate the structures and properties of molecules and solids.}}

{{term|[[Computational complexity theory|computational complexity theory]]}}
{{defn|A subfield of {{gli|computational science}} which focuses on classifying computational problems according to their inherent difficulty, and relating these classes to each other. A computational problem is a task solved by a computer. A computation problem is solvable by mechanical application of mathematical steps, such as an {{gli|algorithm}}.}}

{{term|[[Computational model|computational model]]}}
{{defn|A [[Mathematical model|mathematical model]] in {{gli|computational science}} that requires extensive [[Computational resource|computational resource]]s to study the behavior of a complex system by [[Computer simulation|computer simulation]].<ref>{{cite book |editor-last=Melnik |editor-first=Roderick |title=Mathematical and Computational Modeling: With Applications in Natural and Social Sciences, Engineering, and the Arts |publisher=Wiley |year=2015 |isbn=978-1-118-85398-6 }}</ref>}}

{{term|[[Computational neuroscience|computational neuroscience]]}}
{{ghat|Also '''theoretical neuroscience''' or '''mathematical neuroscience'''.}}
{{defn|A branch of [[Biology:Neuroscience|neuroscience]] which employs mathematical models, theoretical analysis, and abstractions of the brain to understand the principles that govern the development, [[Biology:Neuroanatomy|structure]], [[Biology:Neurophysiology|physiology]], and [[Cognitive neuroscience|cognitive abilities]] of the [[Biology:Nervous system|nervous system]].<ref name="Trappenberg 2002">{{Cite book|title=Fundamentals of Computational Neuroscience|url=https://archive.org/details/fundamentalscomp00ttra|url-access=limited|last=Trappenberg|first=Thomas P.|publisher=Oxford University Press Inc.|year=2002|isbn=978-0-19-851582-1|location=United States|page=[https://archive.org/details/fundamentalscomp00ttra/page/n16 1]}}</ref><ref>What is computational neuroscience? Patricia S. Churchland, Christof Koch, Terrence J. Sejnowski. in Computational Neuroscience pp.46-55. Edited by Eric L. Schwartz. 1993. MIT Press {{cite web |url=http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=7195 |title=Computational Neuroscience - the MIT Press |access-date=2009-06-11 |url-status=dead |archive-url=https://web.archive.org/web/20110604124206/http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=7195 |archive-date=2011-06-04 }}</ref><ref>{{cite web|url=https://mitpress.mit.edu/books/theoretical-neuroscience|title=Theoretical Neuroscience|website=The MIT Press|language=en|access-date=2018-05-24|archive-url=https://web.archive.org/web/20180531150713/http://mitpress.mit.edu/books/theoretical-neuroscience|archive-date=2018-05-31|url-status=dead}}</ref><ref>{{ cite book | author1= Gerstner, W. | author2 = Kistler, W. | author3 = Naud, R. | author4 = Paninski, L.| title = Neuronal Dynamics | publisher = {{wipe|Cambridge University Press}} | location = Cambridge, UK | year = 2014 | isbn = 9781107447615}}</ref>}}

{{term|[[Physics:Computational physics|computational physics]]}}
{{defn|Is the study and implementation of [[Numerical analysis|numerical analysis]] to solve problems in [[Physics:Physics|physics]] for which a [[Scientific theory|quantitative theory]] already exists.<ref>Thijssen, Jos (2007). Computational Physics. Cambridge University Press. {{ISBN|978-0521833462}}.</ref> Historically, computational physics was the first application of modern computers in science, and is now a subset of [[Computational science|computational science]].}}

{{term|[[Computational science|computational science]]}}
{{ghat|Also '''scientific computing''' and '''scientific computation''' ('''SC''').}}
{{defn|An interdisciplinary field that uses advanced computing capabilities to understand and solve complex problems. It is an area of science which spans many disciplines, but at its core it involves the development of computer models and simulations to understand complex natural systems.}}

{{term|[[Computational steering|computational steering]]}}
{{defn|Is the practice of manually intervening with an otherwise autonomous computational process, to change its outcome.}}

{{term|[[Computer|computer]]}}
{{defn|A device that can be instructed to carry out sequences of arithmetic or [[Boolean algebra|logical]] operations automatically via {{gli|computer programming}}. Modern computers have the ability to follow generalized sets of operations, called {{gli|computer program|programs}}. These programs enable computers to perform an extremely wide range of tasks.}}

{{term|[[Computer architecture|computer architecture]]}}
{{defn|A set of rules and methods that describe the functionality, organization, and implementation of {{gli|computer}} systems. Some definitions of architecture define it as describing the capabilities and programming model of a computer but not a particular implementation.<ref>{{cite book|last1=Clements|first1=Alan|title=Principles of Computer Hardware|page=1|edition=Fourth|quote=Architecture describes the internal organization of a computer in an abstract way; that is, it defines the capabilities of the computer and its programming model. You can have two computers that have been constructed in different ways with different technologies but with the same architecture.}}</ref> In other definitions computer architecture involves [[Instruction set architecture|instruction set architecture]] design, [[Microarchitecture|microarchitecture]] design, logic design, and [[Implementation|implementation]].<ref>{{cite book|last1=Hennessy|first1=John|last2=Patterson|first2=David|title=Computer Architecture: A Quantitative Approach|page=11|edition=Fifth|quote=This task has many aspects, including instruction set design, functional organization, logic design, and implementation.}}</ref>}}

{{term|[[Computer data storage|computer data storage]]}}
{{ghat|Also simply '''storage''' or '''memory'''.}}
{{defn|A technology consisting of {{gli|computer}} components and [[Engineering:Data storage device|recording media]] that are used to retain digital [[Data (computing)|data]]. Data storage is a core function and fundamental component of all modern computer systems.<ref name="Patterson" />{{rp|15–16}}}}

{{term|[[Computer ethics|computer ethics]]}}
{{defn|A part of [[Philosophy:Practical philosophy|practical philosophy]] concerned with how computing professionals should make decisions regarding professional and social conduct.<ref name=BynumVeryShort>{{cite web |url=http://www.southernct.edu/organizations/rccs/resources/research/introduction/bynum_shrt_hist.html#maner|title=A Very Short History of Computer Ethics |last= Bynum |first=Terrell Ward |publisher=Southern Connecticut Wein University|access-date=2011-01-05|archive-url=https://web.archive.org/web/20080418122849/http://www.southernct.edu/organizations/rccs/resources/research/introduction/bynum_shrt_hist.html|archive-date=2008-04-18}}</ref>}}

{{term|[[Computer graphics|computer graphics]]}}
{{defn|Pictures and films created using computers. Usually, the term refers to computer-generated image data created with the help of specialized graphical hardware and software. It is a vast and recently developed area of computer science.}}

{{term|[[Computer network|computer network]]}}
{{ghat|Also '''data network'''.}}
{{defn|A digital [[Telecommunications network|telecommunications network]] which allows [[Node (networking)|nodes]] to share resources. In computer networks, computing devices [[Data transmission|exchange data]] with each other using connections ([[Data link|data link]]s) between nodes. These data links are established over [[Networking cable|cable media]] such as wires or optic cables, or [[Engineering:Wireless network|wireless media]] such as {{gli|Wi-Fi}}.}}

{{term|[[Computer program|computer program]]}}
{{defn|Is a collection of instructions<ref name="aup-ch4-p132">{{cite book
  | last = Rochkind
  | first = Marc J.
  | title = Advanced Unix Programming, Second Edition
  | publisher = Addison-Wesley
  | year = 2004
  | page = 1.1.2
}}</ref> that can be [[Execution (computing)|executed]] by a [[Computer|computer]] to perform a specific task. }}

{{term|[[Computer programming|computer programming]]}}
{{defn|The process of designing and building an {{gli|executable}} {{gli|computer program}} for accomplishing a specific {{gli|computing}} task. Programming involves tasks such as analysis, generating {{gli|algorithm|algorithms}}, profiling algorithms' accuracy and resource consumption, and the implementation of algorithms in a chosen {{gli|programming language}} (commonly referred to as '''coding'''<ref name="tumblr2014"/><ref name="tumblr1"/>). The {{gli|source code}} of a program is written in one or more programming languages. The purpose of programming is to find a sequence of instructions that will automate the performance of a task for solving a given problem. The process of programming thus often requires expertise in several different subjects, including knowledge of the {{gli|domain|application domain}}, specialized algorithms, and formal [[Logic|logic]].}}

{{term|[[Computer science|computer science]]}}
{{defn|The theory, experimentation, and engineering that form the basis for the design and use of {{gli|computer|computers}}. It involves the study of {{gli|algorithm|algorithms}} that process, store, and communicate [[Digital data|digital information]]. A {{gli|computer scientist}} specializes in the theory of {{gli|computation}} and the design of computational systems.<ref>{{cite web |url=http://wordnetweb.princeton.edu/perl/webwn?s=computer%20scientist |title=WordNet Search—3.1 |publisher=Wordnetweb.princeton.edu |access-date=14 May 2012}}</ref>}}

{{term|[[Computer scientist|computer scientist]]}}
{{defn|A person who has acquired the knowledge of {{gli|computer science}}, the study of the theoretical foundations of information and computation and their application.<ref>{{cite book |last1=Orsucci |first1=Franco F. |last2=Sala |first2=Nicoletta |date=2008 |title=Reflexing Interfaces: The Complex Coevolution of Information Technology Ecosystems, Information Science Reference |url=https://archive.org/details/reflexinginterfa00orsu_453|url-access=limited |page=[https://archive.org/details/reflexinginterfa00orsu_453/page/n359 335] }}</ref>}}

{{term|[[Computer security|computer security]]}}
{{ghat|Also '''cybersecurity'''<ref>{{Cite journal|last1=Schatz|first1=Daniel|last2=Bashroush|first2=Rabih|last3=Wall|first3=Julie|date=2017|title=Towards a More Representative Definition of Cyber Security|url=https://commons.erau.edu/jdfsl/vol12/iss2/8/|journal=Journal of Digital Forensics, Security and Law|language=en|volume=12|issue=2|issn=1558-7215}}</ref> or '''information technology security''' ('''IT security''').}}
{{defn|The protection of computer systems from theft or damage to their [[Computer hardware|hardware]], {{gli|software}}, or [[Data (computing)|electronic data]], as well as from [[Denial-of-service attack|disruption]] or [[Botnet|misdirection]] of the services they provide.}}

{{term|[[Computer vision|computer vision]]}}
{{defn|An interdisciplinary scientific field that deals with how computers can be made to gain high-level understanding from [[Digital image|digital image]]s or [[Engineering:Video|video]]s. From the perspective of engineering, it seeks to automate tasks that the human visual system can do.<ref>Dana H. Ballard; Christopher M. Brown (1982). Computer Vision. Prentice Hall. {{ISBN|0-13-165316-4}}.</ref><ref>Huang, T. (1996-11-19). Vandoni, Carlo, E, ed. Computer Vision : Evolution And Promise (PDF). 19th CERN School of Computing. Geneva: CERN. pp. 21–25. doi:10.5170/CERN-1996-008.21. {{ISBN|978-9290830955}}.</ref><ref>Milan Sonka; Vaclav Hlavac; Roger Boyle (2008). Image Processing, Analysis, and Machine Vision. Thomson. {{ISBN|0-495-08252-X}}.</ref>}}

{{term|[[Computing|computing]]}}

{{term|[[Concatenation|concatenation]]}}
{{defn|In [[Formal language|formal language theory]] and [[Computer programming|computer programming]], string concatenation  is the operation of joining character strings end-to-end.  For example, the concatenation of "snow" and "ball" is "snowball". In certain formalisations of [[Philosophy:Concatenation theory|concatenation theory]], also called string theory, string concatenation is a [[Primitive notion|primitive notion]].}}

{{term|[[Concurrency (computer science)|Concurrency]]}}
{{defn|The ability of different parts or units of a program, algorithm, or problem to be executed out-of-order or in partial order, without affecting the final outcome.  This allows for parallel execution of the concurrent units, which can significantly improve overall speed of the execution in multi-processor and multi-core systems. In more technical terms, concurrency refers to the decomposability property of a program, algorithm, or problem into order-independent or partially-ordered components or units.<ref>{{cite journal|last1=Lamport|first1=Leslie|title=Time, Clocks, and the Ordering of Events in a Distributed System|journal=Communications of the ACM|volume=21|issue=7|pages=558–565|date=July 1978|url=http://research.microsoft.com/en-us/um/people/lamport/pubs/time-clocks.pdf|access-date=4 February 2016|doi=10.1145/359545.359563|citeseerx=10.1.1.142.3682|s2cid=215822405}}</ref>}}

{{term|[[Conditional (computer programming)|conditional]]}}
{{ghat|Also '''conditional statement''', '''conditional expression''', and '''conditional construct'''.}}
{{defn|A feature of a {{gli|programming language}} which performs different computations or actions depending on whether a programmer-specified [[Boolean data type|Boolean]] condition evaluates to true or false. Apart from the case of branch predication, this is always achieved by selectively altering the {{gli|control flow}} based on some condition.}}

{{term|[[Container (abstract data type)|container]]}}
{{defn|Is a class, a [[Data structure|data structure]],<ref>Paul E. Black (ed.), entry for ''data structure'' in ''[[Dictionary of Algorithms and Data Structures]]. US [[Organization:National Institute of Standards and Technology|National Institute of Standards and Technology]].15 December 2004. Accessed 4 Oct 2011.</ref><ref>Entry ''data structure'' in the [[Encyclopædia Britannica]] (2009) [http://www.britannica.com/EBchecked/topic/152190/data-structure Online entry] Accessed 4 Oct 2011.</ref> or an [[Abstract data type|abstract data type]] (ADT) whose instances are collections of other objects. In other words, they store objects in an organized way that follows specific access rules. The size of the container depends on the number of objects (elements) it contains. Underlying (inherited) implementations of various container types may vary in size and complexity, and provide flexibility in choosing the right implementation for any given scenario.}}

{{term|[[Continuation-passing style|continuation-passing style]] (CPS)}}{{anchor|continuation-passing style}}
{{defn|A style of {{gli|functional programming}} in which {{gli|control flow|control}} is passed explicitly in the form of a [[Continuation|continuation]]. This is contrasted with [[Direct style|direct style]], which is the usual style of programming. [[Biography:Gerald Jay Sussman|Gerald Jay Sussman]] and Guy L. Steele, Jr. coined the phrase in [[AI Memo]] 349 (1975), which sets out the first version of the [[Scheme (programming language)|Scheme]] programming language.<ref>{{cite journal|last1=Sussman|first1=Gerald Jay|last2=Steele|first2=Guy L. Jr. |date=December 1975|title=Scheme: An interpreter for extended lambda calculus|journal=[[AI Memo]]|volume=349|page=19|quote=That is, in this '''continuation-passing programming style''', ''a function always "returns" its result by "sending" it to another function''. This is the key idea.|title-link=wikisource:Scheme: An interpreter for extended lambda calculus}}</ref><ref>{{cite journal|last1=Sussman|first1=Gerald Jay|last2=Steele|first2=Guy L. Jr. |author2-link=Guy L. Steele, Jr.|date=December 1998|title=Scheme: A Interpreter for Extended Lambda Calculus|url=http://www.brics.dk/~hosc/local/HOSC-11-4-pp405-439.pdf|format=reprint|journal=Higher-Order and Symbolic Computation|volume=11|issue=4|pages=405–439|doi=10.1023/A:1010035624696|s2cid=18040106|quote=We believe that this was the first occurrence of the term "'''continuation-passing style'''" in the literature. It has turned out to be an important concept in source code analysis and transformation for compilers and other metaprogramming tools. It has also inspired a set of other "styles" of program expression.|author1-link=Gerald Jay Sussman}}</ref>}}

{{term|[[Control flow|control flow]]}}
{{ghat|Also '''flow of control'''.}}
{{defn|The order in which individual [[Statement (computer science)|statements]], instructions or function calls of an [[Imperative programming|imperative]] [[Computer program|program]] are [[Execution (computing)|executed]] or evaluated. The emphasis on explicit control flow distinguishes an ''[[Imperative programming|imperative programming]]'' language from a ''[[Declarative programming|declarative programming]]'' language.}}

{{term|[[Organization:Creative Commons|Creative Commons]] (CC)}}{{anchor|Creative Commons}}
{{defn|An American non-profit organization devoted to expanding the range of creative works available for others to build upon legally and to share.<ref>{{cite web |url=https://creativecommons.org/faq/|title=Frequently Asked Questions |publisher=Creative Commons |date=4 August 2016|access-date=20 December 2011}}</ref> The organization has released several [[Copyright|copyright]]-[[Finance:License|license]]s, known as [[Creative Commons license]]s, free of charge to the public.}}

{{term|[[Cryptography|cryptography]]}}
{{defn|Or cryptology,  is the practice and study of techniques for [[Secure communication|secure communication]] in the presence of third parties called [[Adversary (cryptography)|adversaries]].<ref name="rivest90">{{cite book|first=Ronald L.|last=Rivest|editor=J. Van Leeuwen|title=Handbook of Theoretical Computer Science|chapter=Cryptography|volume=1|publisher=Elsevier|year=1990}}</ref> More generally, cryptography is about constructing and analyzing protocols that prevent third parties or the public from reading private messages;<ref name="modern-crypto">{{Cite book|first1=Mihir|last1=Bellare|first2=Phillip|last2=Rogaway|title=Introduction to Modern Cryptography|chapter=Introduction|page=10|date=21 September 2005}}</ref> various aspects in [[Information security|information security]] such as data [[Confidentiality|confidentiality]], [[Data integrity|data integrity]], [[Authentication|authentication]], and [[Non-repudiation|non-repudiation]]<ref name="hac">{{cite book|url=https://archive.org/details/handbookofapplie0000mene|title=Handbook of Applied Cryptography|last1=Menezes|first1=A.J.|last2=van Oorschot|first2=P.C.|last3=Vanstone|first3=S.A.|year=1997|publisher=Taylor & Francis |isbn=978-0-8493-8523-0}}</ref> are central to modern cryptography. Modern cryptography exists at the intersection of the disciplines of [[Mathematics|mathematics]], [[Computer science|computer science]], [[Electrical engineering|electrical engineering]], communication science, and [[Physics:Physics|physics]]. Applications of cryptography include electronic commerce, chip-based payment cards, digital currencies, [[Password|computer passwords]], and [[Social:Military communications|military communications]].}}

{{term|[[Comma-separated values|CSV]]}}
{{defn|See ''{{gli|comma-separated values}}''.}}

{{term|cyberbullying}}
{{ghat|Also '''cyberharassment''' or '''online bullying'''.}}
{{defn|A form of [[Social:Bullying|bullying]] or harassment using electronic means.}}

{{term|[[Cyberspace|cyberspace]]}}
{{defn|Widespread, interconnected digital [[Engineering:Technology|technology]].}}
{{glossaryend}}

==D==
{{glossary}}
{{term|[[Daemon (computing)|daemon]]}}
{{defn|In [[Computer multitasking|multitasking]] computer [[Operating system|operating system]]s, a daemon ({{IPAc-en|ˈ|d|iː|m|ən}} or {{IPAc-en|ˈ|d|eɪ|m|ən}})<ref name="jargon">{{Cite web|url=http://catb.org/~esr/jargon/html/D/daemon.html |title=daemon |author=Eric S. Raymond |access-date=2008-10-22 |work=[[Jargon File|The Jargon File]] }}</ref> is a [[Computer program|computer program]] that runs as a [[Background process|background process]], rather than being under the direct control of an interactive user. Traditionally, the process names of a daemon end with the letter ''d'', for clarification that the process is in fact a daemon, and for differentiation between a daemon and a normal computer program. For example, {{mono|syslogd}} is a daemon that implements system logging facility, and {{mono|sshd}} is a daemon that serves incoming [[Secure Shell|SSH]] connections.}}

{{term|[[Data (computer science)|Data]]}}

{{term|[[Data center|data center]]}}
{{ghat|Also '''data centre'''.}}
{{defn|A dedicated space used to house {{gli|computer|computer systems}} and associated components, such as telecommunications and [[Computer data storage|data storage systems]]. It generally includes [[Engineering:Redundancy (engineering)|redundant]] or backup components and infrastructure for power supply, data communications connections, environmental controls (e.g. air conditioning and fire suppression) and various security devices.<ref name=NYT92212>{{cite news|title=Power, Pollution and the Internet|url=https://www.nytimes.com/2012/09/23/technology/data-centers-waste-vast-amounts-of-energy-belying-industry-image.html|access-date=2012-09-25|newspaper=The New York Times|date=September 22, 2012|author=James Glanz}}</ref>}}

{{term|[[Database|database]]}}
{{defn|An organized collection of [[Data (computing)|data]], generally stored and accessed electronically from a computer system. Where databases are more complex, they are often developed using formal design and modeling techniques.}}

{{term|[[Data mining|data mining]]}}
{{defn|Is a process of discovering patterns in large [[Data set|data set]]s involving methods at the intersection of [[Machine learning|machine learning]], [[Statistics|statistics]], and database systems.<ref name="acm" /> Data mining is an interdisciplinary subfield of [[Computer science|computer science]] and [[Statistics|statistics]] with an overall goal to extract information (with intelligent methods) from a data set and transform the information into a comprehensible structure for further use.<ref name="acm">{{cite web |url=http://www.kdd.org/curriculum/index.html |title=Data Mining Curriculum |publisher=[[Organization:Association for Computing Machinery|ACM]] [[SIGKDD]] |date=2006-04-30 |access-date=2014-01-27 }}</ref><ref name="brittanica">{{cite web |last=Clifton |first=Christopher |title=Encyclopædia Britannica: Definition of Data Mining |year=2010 |url=http://www.britannica.com/EBchecked/topic/1056150/data-mining |access-date=2010-12-09 }}</ref><ref name="elements">{{cite web|last1=Hastie|first1=Trevor|last2=Tibshirani|first2=Robert|author-link2=Robert Tibshirani|last3=Friedman|first3=Jerome|author-link3=Jerome H. Friedman|title=The Elements of Statistical Learning: Data Mining, Inference, and Prediction|year=2009|url=http://www-stat.stanford.edu/~tibs/ElemStatLearn/|access-date=2012-08-07|archive-url=https://web.archive.org/web/20091110212529/http://www-stat.stanford.edu/~tibs/ElemStatLearn/|archive-date=2009-11-10|url-status=dead}}</ref><ref>{{cite book |author1=Han, Jaiwei |author2=Kamber, Micheline |author3=Pei, Jian |title=Data Mining: Concepts and Techniques|date=2011|publisher=Morgan Kaufmann|isbn=978-0-12-381479-1|edition=3rd}}</ref> Data mining is the analysis step of the "knowledge discovery in databases" process, or KDD.<ref>Fayyad, Usama; Piatetsky-Shapiro, Gregory; Smyth, Padhraic (1996). "From Data Mining to Knowledge Discovery in Databases" (PDF). Retrieved 17 December 2008.</ref> Aside from the raw analysis step, it also involves database and [[Data management|data management]] aspects, [[Data pre-processing|data pre-processing]], [[Statistical model|model]] and [[Statistical inference|inference]] considerations, interestingness metrics, [[Computational complexity theory|complexity]] considerations, post-processing of discovered structures, [[Data visualization|visualization]], and online updating.<ref name="acm" /> }}

{{term|[[Data science|data science]]}}
{{defn|An interdisciplinary field that uses scientific methods, processes, algorithms, and systems to extract knowledge and insights from [[Data|data]] in various forms, both structured and unstructured,<ref>{{Cite journal | last1 = Dhar | first1 = V. | title = Data science and prediction | doi = 10.1145/2500499 | journal = Communications of the ACM | volume = 56 | issue = 12 | pages = 64–73 | year = 2013 | s2cid = 6107147 | url = http://cacm.acm.org/magazines/2013/12/169933-data-science-and-prediction/fulltext}}</ref><ref>{{cite web | url=http://simplystatistics.org/2013/12/12/the-key-word-in-data-science-is-not-data-it-is-science/ | title=The key word in "Data Science" is not Data, it is Science | publisher=Simply Statistics | date=2013-12-12 | author=Jeff Leek |  access-date=2018-12-05 | archive-date=2014-01-02 | archive-url=https://web.archive.org/web/20140102194117/http://simplystatistics.org/2013/12/12/the-key-word-in-data-science-is-not-data-it-is-science/ | url-status=dead }}</ref> similar to {{gli|data mining}}. Data science is a "concept to unify statistics, data analysis, machine learning and their related methods" in order to "understand and analyze actual phenomena" with data.<ref name="Hayashi">{{Cite book|chapter-url=https://www.springer.com/book/9784431702085|title=Data Science, Classification, and Related Methods|last=Hayashi|first=Chikio|chapter=What is Data Science ? Fundamental Concepts and a Heuristic Example |date=1998-01-01|publisher=Springer Japan|isbn=9784431702085|editor-last=Hayashi|editor-first=Chikio|series=Studies in Classification, Data Analysis, and Knowledge Organization|pages=40–51|language=en|doi=10.1007/978-4-431-65950-1_3|editor-last2=Yajima|editor-first2=Keiji|editor-last3=Bock|editor-first3=Hans-Hermann|editor-last4=Ohsumi|editor-first4=Noboru|editor-last5=Tanaka|editor-first5=Yutaka|editor-last6=Baba|editor-first6=Yasumasa}}</ref> It employs techniques and theories drawn from many fields within the context of mathematics, statistics, information science, and {{gli|computer science}}.}}

{{term|[[Data structure|data structure]]}}
{{defn|A data organization, management, and storage format that enables [[Algorithmic efficiency|efficient]] access and modification.<ref>{{Introduction to Algorithms|edition=3}}</ref><ref>{{cite book |last1=Black |first1=Paul E. |editor1-last=Pieterse |editor1-first=Vreda |editor2-last=Black |editor2-first=Paul E. |title=Dictionary of Algorithms and Data Structures [online] |date=15 December 2004 |publisher=[[Organization:National Institute of Standards and Technology|National Institute of Standards and Technology]] |chapter-url=https://xlinux.nist.gov/dads/HTML/datastructur.html |access-date=2018-11-06 |chapter=data structure}}</ref><ref>{{cite encyclopedia |encyclopedia=Encyclopaedia Britannica |title= Data structure |url=https://www.britannica.com/technology/data-structure |access-date=2018-11-06 |date=17 April 2017}}</ref> More precisely, a data structure is a collection of data values, the relationships among them, and the functions or operations that can be applied to the data.<ref>{{Cite book|url=http://dl.acm.org/citation.cfm?id=1074100.1074312|title=Encyclopedia of Computer Science|last1=Wegner|first1=Peter|last2=Reilly|first2=Edwin D.|publisher=John Wiley and Sons |isbn=978-0470864128|location=Chichester, UK|pages=507–512|date=2003-08-29}}</ref>}}

{{term|[[Data type|data type]]}}
{{ghat|Also simply '''type'''.}}
{{defn|An attribute of [[Data|data]] which tells the {{gli|compiler}} or {{gli|interpreter}} how the programmer intends to use the data. Most {{gli|programming language|programming languages}} support common data types of [[Real number|real]], [[Integer (computer science)|integer]], and [[Boolean data type|Boolean]]. A data type constrains the values that an {{gli|expression}}, such as a {{gli|variable}} or a {{gli|function}}, might take. This data type defines the operations that can be done on the data, the meaning of the data, and the way values of that type can be stored. A type of value from which an expression may take its value.<ref>{{FOLDOC|type|new=yes}}</ref><ref>{{cite book |last=Shaffer |first=C. A. |title=Data Structures & Algorithm Analysis in C++ |location=Mineola, NY |publisher=Dover |edition=3rd |year=2011 |at=1.2 |isbn=978-0-486-48582-9 }}</ref>}}

{{term|[[Debugging|debugging]]}}
{{defn|The process of finding and resolving defects or problems within a {{gli|computer program}} that prevent correct operation of {{gli|computer software}} or the system as a whole. Debugging tactics can involve interactive debugging, {{gli|control flow}} analysis, [[Unit testing|unit testing]], [[Integration testing|integration testing]], log file analysis, monitoring at the application or system level, memory dumps, and [[Profiling (computer programming)|profiling]].}}

{{term|[[Declaration (computer programming)|declaration]]}}
{{defn|In {{gli|computer programming}}, a [[Language construct|language construct]] that specifies properties of an {{gli|identifier}}: it declares what a word (identifier) "means".<ref name="c11">"A declaration specifies the interpretation and attributes of a set of identifiers. A ''definition'' of an identifier is a declaration for that identifier that:
* for an object [variable or constant], causes storage to be reserved for that object;
* for a function, includes the function body;
* for an enumeration constant, is the (only) declaration of the identifier;
* for a typedef name, is the first (or only) declaration of the identifier."
C11 specification, 6.7: Declarations, paragraph 5.</ref> Declarations are most commonly used for [[Subroutine|functions]], [[Variable (computer science)|variables]], [[Constant (computer programming)|constants]], and [[Class (computer programming)|classes]], but can also be used for other entities such as enumerations and type definitions.<ref name="c11"/> Beyond the name (the identifier itself) and the kind of entity (function, variable, etc.), declarations typically specify the {{gli|data type}} (for variables and constants), or the [[Type signature|type signature]] (for functions); types may also include dimensions, such as for arrays. A declaration is used to announce the existence of the entity to the {{gli|compiler}}; this is important in those strongly typed languages that require functions, variables, and constants, and their types, to be specified with a declaration before use, and is used in [[Forward declaration|forward declaration]].<ref>{{cite web
| access-date = 2011-06-08
| author = Mike Banahan
| publisher = GBdirect 
| title = 2.5. Declaration of variables
| quote = [A] declaration [...] introduces just the name and type of something but allocates no storage[...].
| url = http://publications.gbdirect.co.uk/c_book/chapter2/variable_declaration.html}}</ref> The term "declaration" is frequently contrasted with the term "definition",<ref name="c11"/> but meaning and usage varies significantly between languages.}}

{{term|[[Digital data|digital data]]}}
{{defn|In [[Information theory|information theory]] and information systems, the discrete, discontinuous [[Representation (mathematics)|representation]] of information or works. Numbers and letters are commonly used representations.}}

{{term|[[Digital signal processing|digital signal processing]] ('''DSP''')}}{{anchor|digital signal processing}}
{{defn|The use of digital processing, such as by computers or more specialized [[Engineering:Digital signal processor|digital signal processor]]s, to perform a wide variety of [[Signal processing|signal processing]] operations.  The signals processed in this manner are a sequence of numbers that represent [[Sampling (signal processing)|samples]] of a continuous variable in a domain such as time, space, or frequency.}}

{{term|[[Discrete event simulation|discrete event simulation]] ('''DES''')}}{{anchor|discrete event simulation}}
{{defn|A model of the operation of a system as a discrete sequence of events in time. Each event occurs at a particular instant in time and marks a change of {{gli|state}} in the system.<ref>{{cite book|title=Simulation – The practice of model development and use|author=Stewart Robinson|publisher=Wiley|year=2004}}</ref> Between consecutive events, no change in the system is assumed to occur; thus the [[Simulation|simulation]] can directly jump in time from one event to the next.}}

{{term|[[Disk storage|disk storage]]}}
{{defn|(Also sometimes called drive storage) is a general category of storage mechanisms where data is recorded by various electronic, magnetic, optical, or mechanical changes to a surface layer of one or more rotating disks. A disk drive is a device implementing such a storage mechanism. Notable types are the [[Engineering:Hard disk drive|hard disk drive]] (HDD) containing a non-removable disk, the [[Floppy disk|floppy disk drive]] (FDD) and its removable [[Floppy disk|floppy disk]], and various [[Engineering:Optical disc drive|optical disc drive]]s (ODD) and associated [[Engineering:Optical disc|optical disc]] media.}}

{{term|[[Distributed computing|distributed computing]]}}
{{defn|A field of {{gli|computer science}} that studies distributed systems. A ''distributed system'' is a system whose components are located on different [[Computer network|networked computers]], which communicate and coordinate their actions by [[Message passing|passing messages]] to one another.<ref name="Coulouris">{{cite book|last=Coulouris|first=George|author2=Jean Dollimore|author3=Tim Kindberg|author4=Gordon Blair|title=Distributed Systems: Concepts and Design|publisher = Addison-Wesley|year=2011|location=Boston|isbn=978-0-132-14301-1|edition=5th}}</ref> The components interact with one another in order to achieve a common goal. Three significant characteristics of distributed systems are: concurrency of components, [[Clock synchronization|lack of a global clock]], and independent failure of components.<ref name="Coulouris" /> Examples of distributed systems vary from [[Service-oriented architecture|SOA-based systems]] to [[Massively multiplayer online game|massively multiplayer online game]]s to [[Peer-to-peer|peer-to-peer applications]].}}

{{term|[[Divide and conquer algorithm|divide and conquer algorithm]]}}
{{defn|An algorithm design paradigm based on multi-branched {{gli|recursion}}. A divide-and-conquer {{gli|algorithm}} works by recursively breaking down a problem into two or more sub-problems of the same or related type, until these become simple enough to be solved directly. The solutions to the sub-problems are then combined to give a solution to the original problem.}}

{{term|[[Domain Name System|DNS]]}}
{{defn|See ''{{gli|Domain Name System}}''.}}

{{term|[[Software documentation|documentation]]}}
{{defn|Written text or illustration that accompanies {{gli|computer software}} or is embedded in the {{gli|source code}}. It either explains how it operates or how to use it, and may mean different things to people in different roles.}}

{{term|[[Software:Domain (software engineering)|domain]]}}
{{defn|Is the targeted subject area of a [[Computer program|computer program]]. It is a term used in [[Software engineering|software engineering]]. Formally it represents the target subject of a specific programming project, whether narrowly or broadly defined.<ref name="Bjørner">{{cite book | last = Bjørner | first = Dines | title = Software Engineering 3 – Domains, Requirements, and Software Design | url = https://www.springer.com/us/book/9783540211518 | access-date = 2016-12-19 | type = book | volume = I | year = 2006 | publisher = Springer Verlag | language = en | isbn = 978-3-540-33653-2 | page = 9 | chapter = The Tryptych of Software Engineering }}</ref>}}

{{term|[[Domain Name System]] (DNS)}}{{anchor|Domain Name System}}
{{defn|A hierarchical and decentralized naming system for computers, services, or other resources connected to the {{gli|Internet}} or to a private network. It associates various information with [[Domain name|domain name]]s assigned to each of the participating entities. Most prominently, it translates more readily memorized domain names to the numerical [[IP address]]es needed for locating and identifying computer services and devices with the underlying [[Communication protocol|network protocol]]s. By providing a worldwide, [[Distributed computing|distributed]] [[Directory service|directory service]], the Domain Name System has been an essential component of the functionality of the Internet since 1985.}}

{{term|[[Double-precision floating-point format|double-precision floating-point format]]}}
{{defn|A [[Computer number format|computer number format]]. It represents a wide dynamic range of numerical values by using a floating {{gli|radix}} point.}}

{{term|[[Download|download]]}}
{{defn|In [[Computer network|computer network]]s, to receive data from a remote system, typically a [[Server (computing)|server]]<ref name="main">{{cite web|url=http://searchnetworking.techtarget.com/definition/downloading|title=What is downloading? - Definition from WhatIs.com|work=SearchNetworkNexting|access-date=2019-03-04|archive-url=https://web.archive.org/web/20190905142601/https://searchnetworking.techtarget.com/definition/downloading|archive-date=2019-09-05|url-status=dead}}</ref> such as a [[Web server|web server]], an [[File Transfer Protocol|FTP]] server, an [[Email|email]] server, or other similar systems. This contrasts with {{gli|upload|uploading}}, where data is sent ''to'' a remote server. A ''download'' is a [[Computer file|file]] offered for downloading or that has been downloaded, or the process of receiving such a file.}}
{{glossaryend}}

==E==
{{glossary}}
{{term|[[Edge device|edge device]]}}
{{defn|A device which provides an entry point into enterprise or service provider core networks. Examples include [[Engineering:Router (computing)|router]]s, routing [[Network switch|switch]]es, [[Engineering:Integrated access device|integrated access device]]s (IADs), multiplexers, and a variety of metropolitan area network (MAN) and [[Wide area network|wide area network]] (WAN) access devices.  Edge devices also provide connections into carrier and service provider networks. An edge device that connects a [[Engineering:Local area network|local area network]] to a high speed switch or backbone (such as an ATM switch) may be called an edge concentrator.}}

{{term|[[Encryption|encryption]]}}
{{defn|In [[Cryptography|cryptography]], encryption is the process of [[Data compression|encoding]] information. This process converts the original representation of the information, known as [[Plaintext|plaintext]], into an alternative form known as [[Ciphertext|ciphertext]]. Ideally, only authorized parties can decipher a ciphertext back to plaintext and access the original information. Encryption does not itself prevent interference but denies the intelligible content to a would-be interceptor. For technical reasons, an encryption scheme usually uses a pseudo-random encryption [[Key (cryptography)|key]] generated by an [[Algorithm|algorithm]]. It is possible to decrypt the message without possessing the key, but, for a well-designed encryption scheme, considerable computational resources and skills are required. An authorized recipient can easily decrypt the message with the key provided by the originator to recipients but not to unauthorized users. Historically, various forms of encryption have been used to aid in cryptography. Early encryption techniques were often utilized in military messaging. Since then, new techniques have emerged and become commonplace in all areas of modern computing.<ref name=":1">{{Cite journal|last=Kessler|first=Gary|date=November 17, 2006|title=An Overview of Cryptography|url=https://www.garykessler.net/library/crypto.html|journal=Princeton University}}</ref> Modern encryption schemes utilize the concepts of [[Public-key cryptography|public-key]] and [[Symmetric-key algorithm|symmetric-key]].<ref name=":1" /> Modern encryption techniques ensure security because modern computers are inefficient at cracking the encryption.}}

{{term|[[Event (computing)|event]]}}
{{defn|An action or occurrence recognized by software, often originating asynchronously from the external environment, that may be handled by the software. Because an event is an entity which encapsulates the action and the contextual variables triggering the action, the acrostic mnemonic "'''E'''xecution '''V'''ariable '''E'''ncapsulating '''N'''amed '''T'''rigger" is often used to clarify the concept.}}

{{term|[[Event-driven programming|event-driven programming]]}}
{{defn|A {{gli|programming paradigm}} in which the {{gli|control flow|flow of the program}} is determined by {{gli|event|events}} such as user actions ([[Computer mouse|mouse]] clicks, key presses), [[Engineering:Sensor|sensor]] outputs, or [[Message passing|messages]] from other programs or {{gli|thread|threads}}. Event-driven programming is the dominant paradigm used in [[Graphical user interface|graphical user interface]]s and other applications (e.g. JavaScript [[Web application|web application]]s) that are centered on performing certain actions in response to {{gli|input/output|user input}}. This is also true of programming for [[Device driver|device driver]]s (e.g. [[P (programming language)|P]] in USB device driver stacks<ref>{{cite web |url=https://www.microsoft.com/en-us/research/publication/p-safe-asynchronous-event-driven-programming/ |title=P: Safe Asynchronous Event-Driven Programming |author=Vivek Gupta |author2=Ethan Jackson |author3=Shaz Qadeer |author4=Sriram Rajamani |website=[[Company:Microsoft|Microsoft]] |date=November 2012 |access-date=20 February 2017}}</ref>).}}

{{term|evolutionary computing}}
{{defn|A family of {{gli|algorithm|algorithms}} for [[Global optimization|global optimization]] inspired by biological evolution, and the subfield of {{gli|artificial intelligence}} and {{gli|soft computing}} studying these algorithms. In technical terms, they are a family of population-based trial-and-error problem-solvers with a [[Metaheuristic|metaheuristic]] or [[Stochastic optimization|stochastic optimization]] character.}}

{{term|[[Executable|executable]]}}
{{ghat|Also '''executable code''', '''executable file''', '''executable program''', or simply '''executable'''.}}
{{defn|Causes a computer "to perform indicated tasks according to encoded instructions,"<ref>{{cite web |url=http://www.merriam-webster.com/dictionary/executable |title=executable |access-date=2008-07-19 |work=Merriam-Webster's Online Dictionary |publisher=Merriam-Webster}}</ref> as opposed to a [[Data (computing)|data file]] that must be parsed by a program to be meaningful. The exact interpretation depends upon the use - while "instructions" is traditionally taken to mean [[Machine code|machine code]] instructions for a physical [[Central processing unit|CPU]], in some contexts a file containing [[Software:Bytecode|bytecode]] or [[Scripting language|scripting language]] instructions may also be considered executable.}}

{{term|executable module}}
{{defn|}}

{{term|[[Execution (computing)|execution]]}}
{{defn|In [[Computer engineering|computer]] and software engineering is the process by which a [[Computer|computer]] or  [[Virtual machine|virtual machine]] executes the instructions of a [[Computer program|computer program]]. Each instruction of a program is a description of a particular 
action which to be carried out in order for a specific problem to be solved; as instructions of a program and therefore the actions they describe are being carried out by an executing machine, specific effects are produced in accordance to the semantics of the instructions being executed. }}

{{term|[[Exception handling|exception handling]]}}
{{defn|The process of responding to the occurrence, during {{gli|computation}}, of ''exceptions'' – anomalous or exceptional conditions requiring special processing – often disrupting the normal flow of {{gli|computer program|program}} {{gli|execution}}. It is provided by specialized {{gli|programming language}} constructs, [[Computer hardware|computer hardware]] mechanisms like [[Interrupt|interrupt]]s, or [[Operating system|operating system]] [[Inter-process communication|IPC]] facilities like [[Signal (IPC)|signals]].}}

{{term|[[Existence detection]]}}
{{defn|An existence check before reading a file can catch and/or prevent a fatal error.}}

{{term|[[Expression (computer science)|expression]]}}
{{defn|In a {{gli|programming language}}, a combination of one or more {{gli|constant|constants}}, {{gli|variable|variables}}, {{gli|operator|operators}}, and {{gli|function|functions}} that the programming language interprets (according to its particular [[Order of operations|rules of precedence]] and of association) and computes to produce ("to return", in a {{gli|state|stateful}} environment) another value. This process, as for mathematical expressions, is called evaluation.}}

{{term|external library}}
{{defn|}}
{{glossaryend}}

==F==
{{glossary}}
{{term|[[Fault-tolerant computer system|fault-tolerant computer system]]}}
{{defn|A system designed around the concept of [[Fault tolerance|fault tolerance]]. In essence, they must be able to continue working to a level of satisfaction in the presence of errors or breakdowns.}}

{{term|[[Feasibility study|feasibility study]]}}
{{defn|An investigation which aims to objectively and rationally uncover the strengths and weaknesses of an existing business or proposed venture, opportunities and threats present in the [[Earth:Natural environment|natural environment]], the resources required to carry through, and ultimately the prospects for success.<ref name="Justis">Justis, R. T. & Kreigsmann, B. (1979). The feasibility study as a tool for venture analysis. ''Business Journal of Small Business Management'' 17 (1) 35-42.</ref><ref>Georgakellos, D. A. & Marcis, A. M. (2009). Application of the semantic learning approach in the feasibility studies preparation training process. ''Information Systems Management'' 26 (3) 231–240.</ref> In its simplest terms, the two criteria to judge feasibility are cost required and value to be attained.<ref>Young, G. I. M. (1970). Feasibility studies. ''Appraisal Journal'' 38 (3) 376-383.</ref>}}

{{term|[[Field (computer science)|field]]}}
{{defn|Data that has several parts, known as a ''[[Record (computer science)|record]],'' can be divided into fields. [[Relational database]]s arrange data as sets of database records, so called [[Software:Row (database)|rows]]. Each record consists of several fields; the fields of all records form the [[Software:Column (database)|columns]].
Examples of fields: name, gender, hair colour. }}

{{term|[[Filename extension|filename extension]]}}
{{defn|An identifier specified as a [[Substring|suffix]] to the [[Filename|name]] of a [[Computer file|computer file]]. The extension indicates a characteristic of the file contents or its intended use.}}

{{term|[[Software:Filter|filter (software)]]}}
{{defn|A {{gli|computer program}} or {{gli|subroutine}} to process a [[Stream (computing)|stream]], producing another stream. While a single filter can be used individually, they are frequently strung together to form a [[Software:Pipeline|pipeline]].}}

{{term|floating point arithmetic}}
{{defn|In [[Computing|computing]], floating-point arithmetic (FP) is arithmetic using formulaic representation of [[Real number|real number]]s as an approximation to support a [[Trade-off|trade-off]] between range and precision. For this reason, floating-point computation is often found in systems which include very small and very large real numbers, which require fast processing times. A number is, in general, represented approximately to a fixed number of [[Significant figures|significant digits]] (the [[Significand|significand]]) and scaled using an [[Exponentiation|exponent]] in some fixed base; the base for the scaling is normally two, ten, or sixteen. A number that can be represented exactly is of the following form:
: <math>\text{significand} \times \text{base}^\text{exponent},</math>
where significand is an [[Integer|integer]], base is an integer greater than or equal to two, and exponent is also an integer.
For example:
: <math>1.2345 = \underbrace{12345}_\text{significand} \times \underbrace{10}_\text{base}\!\!\!\!\!\!^{\overbrace{-4}^\text{exponent}}.</math>}}

{{term|[[For loop|for loop]]}}
{{ghat|Also '''for-loop'''.}} 
{{defn|A {{gli|control flow}} {{gli|statement}} for specifying [[Iteration|iteration]], which allows code to be executed repeatedly. Various keywords are used to specify this statement: descendants of [[ALGOL]] use "for", while descendants of [[Fortran]] use "do". There are also other possibilities, e.g. [[COBOL]] uses "PERFORM VARYING".}}

{{term|[[Formal methods|formal methods]]}}
{{defn|A set of mathematically based techniques for the [[Formal specification|specification]], development, and [[Formal verification|verification]] of {{gli|software}} and [[Computer hardware|hardware]] systems.<ref name="butler">{{cite web|author=R. W. Butler|title=What is Formal Methods?|url=http://shemesh.larc.nasa.gov/fm/fm-what.html|date=2001-08-06|access-date=2006-11-16}}</ref> The use of formal methods for software and hardware design is motivated by the expectation that, as in other engineering disciplines, performing appropriate mathematical analysis can contribute to the reliability and robustness of a design.<ref>{{cite conference|author=C. Michael Holloway|title=Why Engineers Should Consider Formal Methods|url=http://klabs.org/richcontent/verification/holloway/nasa-97-16dasc-cmh.pdf|conference=16th Digital Avionics Systems Conference (27–30 October 1997)|access-date=2006-11-16|url-status=dead|archive-url=https://web.archive.org/web/20061116210448/http://klabs.org/richcontent/verification/holloway/nasa-97-16dasc-cmh.pdf|archive-date=16 November 2006}}</ref>}}

{{term|[[Formal verification|formal verification]]}}
{{defn|The act of [[Mathematical proof|proving]] or disproving the {{gli|correctness}} of intended {{gli|algorithm|algorithms}} underlying a system with respect to a certain [[Formal specification|formal specification]] or property, using {{gli|formal methods}} of mathematics.<ref>{{cite journal|last=Sanghavi|first=Alok|title=What is formal verification?|journal=EE Times Asia|date=May 21, 2010}}</ref>}}

{{term|[[Functional programming|functional programming]]}}
{{defn|A {{gli|programming paradigm}}—a style of building the structure and elements of {{gli|computer program|computer programs}}–that treats {{gli|computation}} as the evaluation of [[Function (mathematics)|mathematical functions]] and avoids changing-state and [[Immutable object|mutable]] data. It is a [[Declarative programming|declarative programming]] paradigm in that programming is done with {{gli|expression|expressions}} or {{gli|declaration|declarations}}<ref name="expression style">{{cite web|url=https://wiki.haskell.org/Declaration_vs._expression_style#Expression_style|title=Declaration vs. expression style - HaskellWiki}}</ref> instead of {{gli|statement|statements}}.}}
{{glossaryend}}

==G==
{{glossary}}
{{term|[[Game theory|game theory]]}}
{{defn|The study of [[Mathematical model|mathematical model]]s of strategic interaction between rational decision-makers.<ref name=Myerson>Myerson, Roger B. (1991). ''Game Theory: Analysis of Conflict,'' Harvard University Press, p.&nbsp;[https://books.google.com/books?id=E8WQFRCsNr0C&pg=PA1 1]. Chapter-preview links, pp. [https://books.google.com/books?id=E8WQFRCsNr0C&pg=PR7 vii–xi].</ref> It has applications in all fields of [[Social:Social science|social science]], as well as in [[Logic|logic]] and {{gli|computer science}}. Originally, it addressed zero-sum games, in which each participant's gains or losses are exactly balanced by those of the other participants. Today, game theory applies to a wide range of behavioral relations, and is now an umbrella term for the [[Science|science]] of logical decision making in humans, animals, and computers.}}

{{term|[[Garbage in, garbage out|garbage in, garbage out]] (GIGO)}}
{{defn|A term used to describe the concept that flawed or nonsense input data produces nonsense [[Input output|output]] or "garbage". It can also refer to the unforgiving nature of {{gli|coding|programming}}, in which a poorly written program might produce nonsensical behavior.}}

{{term|Graphics Interchange Format}}
{{defn|}}

{{term|[[Gigabyte|gigabyte]]}}
{{defn|A multiple of the unit {{gli|byte}} for digital information. The [[SI prefix|prefix]] ''[[Giga-|giga]]'' means 10<sup>9</sup> in the [[International System of Units]] (SI). Therefore, one gigabyte is {{gaps|1|000|000|000|bytes}}.  The unit symbol for the gigabyte is GB.}}

{{term|[[Global variable|global variable]]}}
{{defn|In {{gli|computer programming}}, a variable with global {{gli|scope}}, meaning that it is visible (hence accessible) throughout the program, unless [[Variable shadowing|shadowed]]. The set of all global variables is known as the ''global environment'' or ''global state''. In compiled languages, global variables are generally [[Static variable|static variable]]s, whose extent (lifetime) is the entire runtime of the program, though in interpreted languages (including command-line interpreters), global variables are generally dynamically allocated when declared, since they are not known ahead of time.}}

{{term|[[Graph theory|graph theory]]}}
{{defn|In mathematics, the study of ''[[Graph (discrete mathematics)|graph]]s'', which are mathematical structures used to model pairwise relations between objects. A graph in this context is made up of ''[[Vertex (graph theory)|vertices]]'' (also called ''nodes'' or ''points'') which are connected by ''[[Glossary of graph theory terms#edge|edges]]'' (also called ''links'' or ''lines''). A distinction is made between undirected graphs, where edges link two vertices symmetrically, and directed graphs, where edges link two vertices asymmetrically.}}
{{glossaryend}}

==H==
{{glossary}}
{{term|[[Handle (computing)|handle]]}}
{{defn|In [[Computer programming|computer programming]], a handle is an abstract [[Reference (computer science)|reference]] to a [[System resource|resource]] that is used when application software references blocks of memory or objects that are managed by another system like a [[Database|database]] or an [[Operating system|operating system]].}}

{{term|[[Computational complexity theory|hard problem]]}}
{{defn|Computational complexity theory focuses on classifying computational problems according to their inherent difficulty, and relating these classes to each other. A computational problem is a task solved by a computer. A computation problem is solvable by mechanical application of mathematical steps, such as an algorithm.}}

{{term|[[Hash function|hash function]]}}
{{defn|Any [[Function (mathematics)|function]] that can be used to map [[Data (computing)|data]] of arbitrary size to data of a fixed size. The values returned by a hash function are called '''hash values''', '''hash codes''', '''digests''', or simply '''hashes'''. Hash functions are often used in combination with a [[Hash table|hash table]], a common [[Data structure|data structure]] used in computer software for rapid data lookup. Hash functions accelerate table or database lookup by detecting duplicated records in a large file.}}

{{term|[[Hash table|hash table]]}}
{{defn|In {{gli|computing}}, a '''hash table''' ('''hash map''') is a [[Data structure|data structure]] that implements an [[Associative array|associative array]] [[Abstract data type|abstract data type]], a structure that can map [[Unique key|keys]] to {{gli|value|values}}. A hash table uses a [[Hash function|hash function]] to compute an ''index'' into an array of ''buckets'' or ''slots'', from which the desired value can be found.}}

{{term|[[Heap (data structure)|heap]]}}
{{defn|A specialized [[Tree (data structure)|tree]]-based [[Data structure|data structure]] which is essentially an almost complete<ref>{{Introduction to Algorithms|edition=3|pages=151–152}}</ref> tree that satisfies the ''heap property:'' if P is a parent [[Node (computer science)|node]] of C, then the ''key'' (the ''value'') of P is either greater than or equal to (in a ''max heap'') or less than or equal to (in a ''min heap'') the key of C.<ref>Black (ed.), Paul E. (2004-12-14). Entry for ''heap'' in ''[[Dictionary of Algorithms and Data Structures]]''. Online version. U.S. [[Organization:National Institute of Standards and Technology|National Institute of Standards and Technology]], 14 December 2004. Retrieved on 2017-10-08 from https://xlinux.nist.gov/dads/HTML/heap.html.</ref> The node at the "top" of the heap (with no parents) is called the ''root'' node.}}

{{term|[[Heapsort|heapsort]]}}
{{defn|A [[Comparison sort|comparison-based]] [[Sorting algorithm|sorting algorithm]]. Heapsort can be thought of as an improved [[Selection sort|selection sort]]: like that algorithm, it divides its input into a sorted and an unsorted region, and it iteratively shrinks the unsorted region by extracting the largest element and moving that to the sorted region. The improvement consists of the use of a [[Heap (data structure)|heap]] data structure rather than a linear-time search to find the maximum.<ref>{{cite book |first=Steven |last=Skiena |chapter=Sorting and Searching |date=2012 |title=The Algorithm Design Manual |url=https://archive.org/details/algorithmdesignm00skie_772 |url-access=limited |publisher=Springer |page=[https://archive.org/details/algorithmdesignm00skie_772/page/n120 109] |isbn=978-1-84800-069-8 |quote=[H]eapsort is nothing but an implementation of selection sort using the right data structure.|doi=10.1007/978-1-84800-070-4_4}}<!--DOI for chapter--></ref>}}

{{term|human-computer interaction (HCI)}}
{{defn|Researches the design and use of computer technology, focused on the interfaces between people ([[User (computing)|users]]) and computers. Researchers in the field of HCI both observe the ways in which humans interact with computers and design technologies that let humans interact with computers in novel ways. As a field of research, human–computer interaction is situated at the intersection of {{gli|computer science}}, behavioral sciences, [[Design|design]], [[Social:Media studies|media studies]], and [[Outline of human–computer interaction#Related fields|several other fields of study]].}}
{{glossaryend}}

==I==
{{glossary}}
{{term|[[Identifier (computer science)|identifier]]}}
{{defn|In [[Computer language|computer language]]s, identifiers are tokens (also called [[Symbol|symbol]]s) which name language entities. Some of the kinds of entities an identifier might denote include variables, [[Data type|types]], labels, [[Subroutine|subroutine]]s,  and [[Modular programming|packages]].}}

{{term|[[Integrated development environment|IDE]]}}
{{defn|Integrated development environment.}}

{{term|[[Image processing|image processing]]}}
{{defn|}}

{{term|[[Imperative programming|imperative programming]]}}
{{defn|A {{gli|programming paradigm}} that uses {{gli|statement|statements}} that change a program's {{gli|state}}. In much the same way that the imperative mood in [[Philosophy:Natural language|natural language]]s expresses commands, an imperative program consists of {{gli|command|commands}} for the computer to perform. Imperative programming focuses on describing ''how'' a program operates.}}

{{term|[[Incremental build model|incremental build model]]}}
{{defn|A method of [[Software development|software development]] where the product is [[Software design|designed]], implemented and [[Software testing|tested]] incrementally (a little more is added each time) until the product is finished. It involves both development and maintenance. The product is defined as finished when it satisfies all of its requirements. This model combines the elements of the {{gli|waterfall model}} with the iterative philosophy of [[Software prototyping|prototyping]].}}

{{term|[[Information space analysis|information space analysis]]}}
{{defn|A deterministic method, enhanced by {{gli|artificial intelligence|machine intelligence}}, for locating and assessing {{gli|resource|resources}} for team-centric efforts.}}

{{term|[[Information visualization|information visualization]]}}
{{defn|}}

{{term|inheritance}}
{{defn|In {{gli|object-oriented programming}}, the mechanism of basing an {{gli|object}} or {{gli|class}} upon another object ([[Prototype-based programming|prototype-based inheritance]]) or class ([[Class-based programming|class-based inheritance]]), retaining similar implementation. Also defined as deriving new classes (sub classes) from existing ones (super class or [[Fragile base class|base class]]) and forming them into a hierarchy of classes.}}

{{term|[[Input output|input/output]] (I/O)}}
{{ghat|Also informally '''io''' or '''IO'''.}} 
{{defn|The communication between an information processing system, such as a {{gli|computer}}, and the outside world, possibly a human or another information processing system. [[Information|Inputs]] are the signals or data received by the system and outputs are the signals or [[Data (computing)|data]] sent from it. The term can also be used as part of an action; to "perform I/O" is to perform an input or output operation.}}

{{term|[[Insertion sort|insertion sort]]}}
{{defn|A simple [[Sorting algorithm|sorting algorithm]] that builds the final [[Sorted array|sorted array]] (or list) one item at a time.}}

{{term|[[Instruction cycle|instruction cycle]]}}
{{ghat|Also '''fetch–decode–execute cycle''' or simply '''fetch-execute cycle'''.}}
{{defn|The cycle which the {{gli|central processing unit}} (CPU) follows from {{gli|booting|boot-up}} until the computer has shut down in order to process instructions. It is composed of three main stages: the fetch stage, the decode stage, and the execute stage.}}

{{term|[[Integer (computer science)|integer]]}}
{{defn|A datum of integral data type, a [[Data type|data type]] that represents some [[Interval (mathematics)|range]] of mathematical [[Integer|integer]]s. Integral data types may be of different sizes and may or may not be allowed to contain negative values. Integers are commonly represented in a computer as a group of binary digits (bits). The size of the grouping varies so the set of integer sizes available varies between different types of computers. Computer hardware, including [[Virtual machine|virtual machine]]s, nearly always provide a way to represent a processor register or memory address as an integer.}}

{{term|[[Integrated development environment|integrated development environment]] (IDE)}}{{anchor|integrated development environment}}
{{defn|A software application that provides comprehensive facilities to computer programmers for [[Software development|software development]]. An IDE normally consists of at least a [[Software:Source code editor|source code editor]], [[Software:Build automation|build automation]] tools, and a [[Debugger|debugger]].}}

{{term|[[Integration testing|integration testing]]}}
{{defn|(sometimes called integration and testing, abbreviated I&T) is the phase in [[Software testing|software testing]] in which individual software modules are combined and tested as a group. Integration testing is conducted to evaluate the compliance of a system or component with specified [[Functional requirement|functional requirement]]s.<ref>{{Cite book|title=ISO/IEC/IEEE International Standard - Systems and software engineering|publisher=ISO/IEC/IEEE 24765:2010(E)|year=2010|pages=vol., no., pp.1–418, 15 Dec. 2010}}</ref> It occurs after [[Unit testing|unit testing]] and before [[Software verification and validation|validation testing]]. Integration testing takes as its input modules that have been unit tested, groups them in larger aggregates, applies tests defined in an integration [[Test plan|test plan]] to those aggregates, and delivers as its output the integrated system ready for [[System testing|system testing]].<ref>[https://books.google.com/books?id=utFCImZOTEIC&dq=integration+test&pg=PA73 Martyn A Ould & Charles Unwin (ed), ''Testing in Software Development'', BCS (1986), p71]. Accessed 31 Oct 2014</ref>}}

{{term|[[Social:Intellectual property|intellectual property]] (IP)}}{{anchor|intellectual property}}
{{defn|A category of legal property that includes intangible creations of the human intellect.<ref>{{Cite book|url=https://www.wipo.int/publications/en/details.jsp?id=4080|title=Understanding Industrial Property|publisher=World Intellectual Property Organization|doi=10.34667/tind.28945|access-date=2018-12-06|author1=World Intellectual Property Organization (WIPO)|year=2016|isbn=9789280525885}}</ref><ref>{{Cite web|url=http://www.europarl.europa.eu/factsheets/en/sheet/36/intellectual-industrial-and-commercial-property|title=Intellectual, industrial and commercial property {{!}} Fact Sheets on the European Union|publisher=European Parliament|access-date=2018-12-06}}</ref> There are many types of intellectual property, and some countries recognize more than others.<ref>{{Cite web |url=https://www.wto.org/english/tratop_e/trips_e/intel1_e.htm |title=What are intellectual property rights? |website=World Trade Organization |access-date=2016-05-23}}</ref><ref>"Intellectual property", ''Black's Law Dictionary'', 10th ed. (2014).</ref><ref>{{Cite web|url=https://www.wipo.int/edocs/pubdocs/en/wipo_pub_909_2016.pdf|title=Understanding Copyright and Related Rights|publisher=World Intellectual Property Organization|page=4|access-date=2018-12-06}}</ref><ref>{{Cite web|url=https://www.wipo.int/edocs/pubdocs/en/intproperty/450/wipo_pub_450.pdf|title=What is Intellectual Property?|publisher=World Intellectual Property Organization (WIPO)|access-date=2018-12-07|archive-date=2020-02-06|archive-url=https://web.archive.org/web/20200206072600/https://www.wipo.int/edocs/pubdocs/en/intproperty/450/wipo_pub_450.pdf|url-status=dead}}</ref><ref>{{Cite web|url=https://www.wipo.int/edocs/pubdocs/en/wipo_pub_895_2016.pdf|title=Understanding Industrial Property|publisher=World Intellectual Property Organization (WIPO)|access-date=2018-12-07}}</ref> The most well-known types are [[Copyright|copyright]]s, [[Social:Patent|patent]]s, [[Social:Trademark|trademark]]s, and [[Social:Trade secret|trade secret]]s.}}

{{term|[[Intelligent agent|intelligent agent]]}}
{{defn|In [[Artificial intelligence|artificial intelligence]], an '''intelligent agent''' ('''IA''') refers to an autonomous entity which acts, directing its activity towards achieving goals (i.e. it is an [[Software agent|agent]]), upon an environment using observation through sensors and consequent actuators (i.e. it is intelligent).<ref>{{Cite journal|last1=Anderson|first1=Michael|last2=Anderson|first2=Susan Leigh|date=2007-12-15|title=Machine Ethics: Creating an Ethical Intelligent Agent|url=https://ojs.aaai.org/index.php/aimagazine/article/view/2065|journal=AI Magazine|language=en|volume=28|issue=4|pages=15|doi=10.1609/aimag.v28i4.2065|s2cid=17033332 |issn=2371-9621}}</ref> Intelligent agents may also [[Machine learning|learn]] or use knowledge to achieve their goals. They may be very simple or [[Complexity|very complex]]. A reflex machine, such as a [[Engineering:Thermostat|thermostat]], is considered an example of an intelligent agent.<ref>According to the definition given by {{harvtxt|Russell|Norvig|2003|loc=chpt. 2}}</ref>}}

{{term|[[Interface (computing)|interface]]}}
{{defn|A shared boundary across which two or more separate components of a computer system exchange information. The exchange can be between {{gli|software}}, [[Computer hardware|computer hardware]], [[Engineering:Peripheral|peripheral]] devices, [[User interface|humans]], and combinations of these.<ref name="HookwayInterface14">{{cite book |url=https://books.google.com/books?id=BQM_AwAAQBAJ |chapter=Chapter 1: The Subject of the Interface |title=Interface |author=Hookway, B. |publisher=MIT Press |pages=1–58 |year=2014 |isbn=9780262525503}}</ref> Some computer hardware devices, such as a [[Engineering:Touchscreen|touchscreen]], can both send and receive data through the interface, while others such as a mouse or microphone may only provide an interface to send data to a given system.<ref>{{cite encyclopedia
 | year =2000
 | title =IEEE 100 - The Authoritative Dictionary Of IEEE Standards Terms 
 | publisher =IEEE Press
 | location =NYC, NY, USA
 | isbn =9780738126012
 | pages =574–575
}}</ref>}}

{{term|[[Internal documentation|internal documentation]]}}
{{defn|Computer {{gli|software}} is said to have Internal Documentation if the notes on how and why various parts of code operate is included within the {{gli|source code}} as comments.  It is often combined with meaningful variable names with the intention of providing potential future programmers a means of understanding the workings of the code. This contrasts with external [[Documentation|documentation]], where programmers keep their notes and explanations in a separate document.}}

{{term|[[Internet|internet]]}}
{{defn|The global system of interconnected [[Computer network|computer network]]s that use the [[Internet protocol suite]] (TCP/IP) to link devices worldwide. It is a ''network of networks'' that consists of private, public, academic, business, and government networks of local to global scope, linked by a broad array of electronic, wireless, and optical networking technologies.}}

{{term|internet bot}}
{{ghat|Also '''web robot''', '''robot''', or simply '''bot'''.}}
{{defn|A {{gli|software application}} that runs automated tasks (scripts) over the [[Internet]].<ref>{{cite book |url=https://archive.org/details/malicio_dun_2009_00_4004 |url-access=registration |title=Malicious Bots: An Inside Look into the Cyber-Criminal Underground of the Internet |last1=Dunham |first1=Ken |last2=Melnick |first2=Jim |publisher=CRC Press |year=2008 |isbn=9781420069068 }}</ref> Typically, bots perform tasks that are both simple and structurally repetitive, at a much higher rate than would be possible for a human alone. The largest use of bots is in [[Web crawler|web spidering]] (''web crawler''), in which an automated script fetches, analyzes and files information from web servers at many times the speed of a [[Biology:Human|human]].}}

{{term|[[Interpreter (computing)|interpreter]]}}
{{defn|A {{gli|computer program}} that directly {{gli|execution|executes}} instructions written in a {{gli|programming language|programming}} or [[Scripting language|scripting language]], without requiring them to have been previously {{gli|compiler|compiled}} into a machine language program.}}

{{term|[[Invariant (computer science)|invariant]]}}
{{defn|One can encounter invariants that can be relied upon to be true during the execution of a program, or during some portion of it. It is a [[Logical assertion|logical assertion]] that is always held to be true during a certain phase of execution. For example, a [[Loop invariant|loop invariant]] is a condition that is true at the beginning and the end of every execution of a loop.}}

{{term|[[Iteration|iteration]]}}
{{defn|Is the repetition of a process in order to generate an outcome. The sequence will approach some end point or end value. Each repetition of the process is a single iteration, and the outcome of each iteration is then the starting point of the next iteration.  In [[Mathematics|mathematics]] and [[Computer science|computer science]], iteration (along with the related technique of [[Recursion|recursion]]) is a standard element of [[Algorithm|algorithm]]s.}}
{{glossaryend}}

==J==
{{glossary}}
{{term|[[Java (programming language)|Java]]}}
{{defn|A [[General-purpose language|general-purpose]] {{gli|programming language}} that is [[Class-based programming|class-based]], {{gli|object-oriented programming|object-oriented}}{{sfn|Gosling|Joy|Steele|Bracha|2014|p=1}}(although not a ''pure'' OO language<ref>{{cite web|url=https://stackoverflow.com/questions/12836522/java-is-pure-object-oriented-or-not|title=Java is pure object oriented or not?|website=Stack Overflow|access-date=2019-05-24}}</ref>), and designed to have as few implementation {{gli|dependency|dependencies}} as possible. It is intended to let application developers "[[Write once, run anywhere|write once, run anywhere]]" (WORA),<ref>{{cite web|url=http://www.computerweekly.com/Articles/2002/05/02/186793/write-once-run-anywhere.htm|title=Write once, run anywhere?|date=May 2, 2002|publisher=Computer Weekly|access-date=2009-07-27}}</ref> meaning that {{gli|compiler|compiled}} Java code can run on all platforms that support Java without the need for recompilation.<ref name="design_goals">{{cite web|url=https://www.oracle.com/technetwork/java/intro-141325.html|title=1.2 Design Goals of the Java™ Programming Language|publisher=Oracle|date=January 1, 1999|access-date=2013-01-14|archive-url=https://web.archive.org/web/20130123204103/http://www.oracle.com/technetwork/java/intro-141325.html|archive-date=January 23, 2013|url-status=live|df=mdy-all}}</ref>}}
{{glossaryend}}

==K==
{{glossary}}
{{term|[[Software:Kernel (operating system)|kernel]]}}
{{defn|The first section of an {{gli|operating system}} to load into {{gli|data storage|memory}}. As the center of the operating system, the kernel needs to be small, efficient, and loaded into a protected area in the memory so that it cannot be overwritten. It may be responsible for such essential tasks as disk drive management, file management, memory management, process management, etc.}}
{{glossaryend}}

==L==
{{glossary}}
{{term|[[Library (computing)|library (computing)]]}}
{{defn|A collection of [[Non-volatile memory|non-volatile]] resources used by {{gli|computer program|computer programs}}, often for [[Software development|software development]]. These may include configuration data, documentation, help data, message templates, [[Code reuse|pre-written code]] and {{gli|subroutine|subroutines}}, {{gli|class|classes}}, {{gli|value|values}}, or {{gli|data type|type}} specifications.}}

{{term|[[Linear search|linear search]]}}
{{ghat|Also '''sequential search'''.}}
{{defn|A method for finding an element within a {{gli|list}}. It sequentially checks each element of the list until a match is found or the whole list has been searched.{{Sfn|Knuth|1998|loc=§6.1 ("Sequential search")}}}}

{{term|linked list}}
{{defn|A linear collection of data elements, whose order is not given by their physical placement in memory. Instead, each element [[Pointer (computer programming)|points]] to the next. It is a [[Data structure|data structure]] consisting of a collection of [[Node (computer science)|node]]s which together represent a [[Sequence|sequence]].}}

{{term|[[Linker (computing)|linker]]}}
{{defn| or link editor, is a computer utility program that takes one or more [[Object file|object file]]s generated by a {{gli|compiler}} or an [[Assembler (computing)|assembler]] and combines them into a single [[Executable|executable]] file, [[Library (computing)|library]] file, or another 'object' file.  A simpler version that writes its output directly to memory is called the ''loader'', though [[Software:Loader (computing)|loading]] is typically considered a separate process.<ref>{{cite book |last=IBM Corporation |title=IBM OS Linkage Editor and Loader |year=1972 |url= http://bitsavers.informatik.uni-stuttgart.de/pdf/ibm/360/os/R21.0_Mar72/GC28-6538-9_OS_Linkage_Editor_and_Loader_Release_21_Jan72.pdf}}</ref>}}

{{term|[[List (abstract data type)|list]]}}
{{defn|An [[Abstract data type|abstract data type]] that represents a countable number of ordered {{gli|value|values}}, where the same value may occur more than once. An instance of a list is a computer representation of the mathematical concept of a finite sequence; the (potentially) infinite analog of a list is a {{gli|stream}}.<ref>{{cite book |title=Structure and Interpretation of Computer Programs |first1=Harold |last1=Abelson |first2=Gerald Jay |last2=Sussman |year=1996 |publisher=MIT Press|title-link=Structure and Interpretation of Computer Programs }}</ref>{{rp|§3.5}} Lists are a basic example of {{gli|container|containers}}, as they contain other values. If the same value occurs multiple times, each occurrence is considered a distinct item.}}

{{term|[[Software:Loader (computing)|loader]]}}
{{defn|The part of an [[Operating system|operating system]] that is responsible for loading [[Computer program|programs]] and [[Library (computing)|libraries]]. It is one of the essential stages in the process of starting a program, as it places programs into memory and prepares them for execution. Loading a program involves reading the contents of the [[Executable|executable file]] containing the program instructions into memory, and then carrying out other required preparatory tasks to prepare the executable for running. Once loading is complete, the operating system starts the program by passing control to the loaded program code.}}

{{term|[[Logic error|logic error]]}}
{{defn|In {{gli|computer programming}}, a [[Software bug|bug]] in a program that causes it to operate incorrectly, but not to terminate abnormally (or [[Crash (computing)|crash]]). A logic error produces unintended or undesired output or other behaviour, although it may not immediately be recognized as such.}}

{{term|[[Logic programming|logic programming]]}}
{{defn|A type of {{gli|programming paradigm}} which is largely based on formal logic. Any program written in a logic {{gli|programming language}} is a set of sentences in logical form, expressing facts and rules about some problem domain.  Major logic programming language families include [[Prolog]], [[Answer set programming|answer set programming]] (ASP), and [[Datalog]].}}
{{glossaryend}}

==M==
{{glossary}}
{{term|[[Machine learning|machine learning]] (ML)}}{{anchor|machine learning}}
{{defn|The scientific study of {{gli|algorithm|algorithms}} and [[Statistical model|statistical model]]s that [[Computer systems|computer systems]] use to perform a specific task without using explicit instructions, relying on patterns and [[Philosophy:Inference|inference]] instead. It is seen as a subset of [[Artificial intelligence|artificial intelligence]]. Machine learning algorithms build a [[Mathematical model|mathematical model]] based on sample data, known as "training data", in order to make predictions or decisions without being explicitly programmed to perform the task.{{refn|The definition "without being explicitly programmed" is often attributed to [[Biography:Arthur Samuel (computer scientist)|Arthur Samuel]], who coined the term "machine learning" in 1959, but the phrase is not found verbatim in this publication, and may be a paraphrase that appeared later. Confer "Paraphrasing Arthur Samuel (1959), the question is: How can computers learn to solve problems without being explicitly programmed?" in {{Cite conference|title=Automated Design of Both the Topology and Sizing of Analog Electrical Circuits Using Genetic Programming|conference=Artificial Intelligence in Design '96|last1=Koza|first1=John R.|last2=Bennett|first2=Forrest H.|last3=Andre|first3=David|last4=Keane|first4=Martin A.|date=1996|publisher=Springer, Dordrecht|pages=151–170|language=en|doi=10.1007/978-94-009-0279-4_9}}}}<ref>< Bishop, C. M. (2006), Pattern Recognition and Machine Learning, Springer, {{ISBN|978-0-387-31073-2}}</ref>}}

{{term|[[Machine vision|machine vision]] (MV)}}{{anchor|machine vision}}
{{defn|The technology and methods used to provide imaging-based automatic inspection and analysis for such applications as automatic inspection, [[Process control|process control]], and robot guidance, usually in industry. Machine vision refers to many technologies, software and hardware products, integrated systems, actions, methods and expertise. Machine vision as a [[Engineering:Systems engineering|systems engineering]] discipline can be considered distinct from [[Computer vision|computer vision]], a form of {{gli|computer science}}. It attempts to integrate existing technologies in new ways and apply them to solve real world problems. The term is the prevalent one for these functions in industrial automation environments but is also used for these functions in other environments such as security and vehicle guidance.}}

{{term|[[Mathematical logic|mathematical logic]]}}
{{defn|A subfield of [[Mathematics|mathematics]] exploring the applications of formal [[Logic|logic]] to mathematics.  It bears close connections to [[Metamathematics|metamathematics]], the [[Philosophy:Foundations of mathematics|foundations of mathematics]], and [[Theoretical computer science|theoretical computer science]].<ref>Undergraduate texts include Boolos, Burgess, and Jeffrey (2002), [[Biography:Herbert Enderton|Enderton]] (2001), and Mendelson (1997). A classic graduate text by Shoenfield (2001) first appeared in 1967.</ref> The unifying themes in mathematical logic include the study of the expressive power of [[Formal system|formal system]]s and the [[Deductive reasoning|deductive]] power of formal [[Mathematical proof|proof]] systems.}}

{{term|[[Matrix (mathematics)|matrix]]}}
{{defn|In [[Mathematics|mathematics]], a matrix, (plural matrices), is a [[Rectangle|rectangular]] ''array''<ref>Equivalently, ''table''.</ref> (see [[Irregular matrix|irregular matrix]]) of [[Number|number]]s, [[Symbol (formal)|symbol]]s, or [[Expression (mathematics)|expression]]s, arranged in ''rows'' and ''columns''.<ref>{{harvtxt|Anton|1987|p=23}}</ref><ref>{{harvtxt|Beauregard|Fraleigh|1973|p=56}}</ref>}}

{{term|[[Computer data storage|memory]]}}
{{defn|Computer data storage, often called storage, is a technology consisting of [[Computer|computer]] components and [[Engineering:Data storage device|recording media]] that are used to retain digital [[Data (computing)|data]]. It is a core function and fundamental component of computers.<ref name="Patterson">{{Cite book |title=Computer Organization and Design: The Hardware/Software Interface |last1=Patterson |first1=David A. |last2=Hennessy |first2=John L. |date=2005 |publisher=Morgan Kaufmann Publishers |isbn=1-55860-604-1 |edition=3rd |location=[[Place:Amsterdam|Amsterdam]] |oclc=56213091 |url-access=registration |url=https://archive.org/details/isbn_9781558606043 }}</ref>{{rp|15–16}}}}

{{term|[[Merge sort|merge sort]]}}
{{ghat|Also '''mergesort'''.}}

{{defn|An efficient, general-purpose, [[Comparison sort|comparison-based]] [[Sorting algorithm|sorting algorithm]]. Most implementations produce a [[Sorting algorithm#Stability|stable sort]], which means that the order of equal elements is the same in the input and output. Merge sort is a [[Divide and conquer algorithm|divide and conquer algorithm]] that was invented by [[Biography:John von Neumann|John von Neumann]] in 1945.<ref>{{Harvtxt|Knuth|1998|p=158}}</ref> A detailed description and analysis of bottom-up mergesort appeared in a report by [[Biography:Herman Goldstine|Goldstine]] and [[Biography:John von Neumann|von Neumann]] as early as 1948.<ref>{{cite conference |title=A meticulous analysis of mergesort programs |date=March 1997 |first1=Jyrki |last1=Katajainen |first2=Jesper Larsson |last2=Träff |conference=Italian Conference on Algorithms and Complexity |location=Rome |book-title=Proceedings of the 3rd Italian Conference on Algorithms and Complexity |pages=217–228 |doi=10.1007/3-540-62592-5_74 |citeseerx=10.1.1.86.3154  |url=http://hjemmesider.diku.dk/~jyrki/Paper/CIAC97.pdf }}</ref>}}

{{term|method}}
{{defn|In {{gli|object-oriented programming}} (OOP), a {{gli|procedure}} associated with a [[Message passing|message]] and an {{gli|object}}. An object consists of data and behavior. The data and behavior comprise an interface, which specifies how the object may be utilized by any of various consumers<ref name="consumerdef001a">Consumers of an object may consist of various kinds of elements, such as other programs, remote computer systems, or computer programmers who wish to utilize the object as part of their own programs.</ref> of the object.}}

{{term|[[Software development process|methodology]]}}
{{defn|In [[Software engineering|software engineering]], a software development process is the process of dividing [[Software development|software development]] work into distinct phases to improve [[Software design|design]], [[Software product management|product management]], and [[Software project management|project management]]. It is also known as a software development life cycle (SDLC). The methodology may include the pre-definition of specific deliverables and artifacts that are created and completed by a project team to develop or maintain an application.<ref name="Medicare 2008">Centers for Medicare & Medicaid Services (CMS) Office of Information Service (2008). Selecting a development approach. Webarticle. United States Department of Health and Human Services (HHS). Re-validated: March 27, 2008. Retrieved 27 Oct 2008.</ref>}}

{{term|[[Modem|modem]]}}
{{ghat|Portmanteau of '''modulator-demodulator'''.}}
{{defn|A [[Computer hardware|hardware]] device that converts data into a format suitable for a [[Physics:Transmission medium|transmission medium]] so that it can be transmitted from one computer to another (historically along telephone wires). A modem [[Engineering:Modulation#Digital modulation methods|modulates]] one or more [[Carrier wave|carrier wave]] signals to encode digital information for transmission and demodulates signals to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded reliably to reproduce the original digital data. Modems can be used with almost any means of transmitting analog signals from [[Engineering:Light-emitting diode|light-emitting diode]]s to [[Social:Radio|radio]]. A common type of modem is one that turns the [[Digital data|digital data]] of a [[Computer|computer]] into modulated electrical signal for transmission over [[Engineering:Telephone line|telephone line]]s and demodulated by another modem at the receiver side to recover the digital data.}}
{{glossaryend}}

==N==
{{glossary}}
{{term|[[Natural language processing|natural language processing]] (NLP)}}
{{defn|A subfield of [[Social:Linguistics|linguistics]], {{gli|computer science}}, [[Information engineering (field)|information engineering]], and [[Artificial intelligence|artificial intelligence]] concerned with the interactions between computers and human (natural) languages, in particular how to program computers to process and analyze large amounts of [[Philosophy:Natural language|natural language]] data.  Challenges in natural language processing frequently involve [[Speech recognition|speech recognition]], natural language understanding, and [[Natural language generation|natural language generation]].}}

{{term|[[Node (computer science)|node]]}}
{{defn|Is a basic unit of a [[Data structure|data structure]], such as a linked list or [[Tree (data structure)|tree]] data structure. Nodes contain [[Data|data]] and also may link to other nodes. Links between nodes are often implemented by [[Pointer (computer programming)|pointers]].}}

{{term|[[Number theory|number theory]]}}
{{defn|A branch of [[Pure mathematics|pure mathematics]] devoted primarily to the study of the [[Integer|integer]]s and [[Arithmetic function|integer-valued functions]].}}

{{term|[[Numerical analysis|numerical analysis]]}}
{{defn|The study of {{gli|algorithm|algorithms}} that use numerical [[Approximation|approximation]] (as opposed to symbolic manipulations) for the problems of [[Mathematical analysis|mathematical analysis]] (as distinguished from [[Discrete mathematics|discrete mathematics]]).}}

{{term|[[Numerical method|numerical method]]}}
{{defn|In [[Numerical analysis|numerical analysis]], a numerical method is a mathematical tool designed to solve numerical problems. The implementation of a numerical method with an appropriate convergence check in a programming language is called a numerical algorithm.}}
{{glossaryend}}

==O==
{{glossary}}
{{term|[[Object (computer science)|object]]}}
{{defn|An object can be a [[Variable (computer science)|variable]], a [[Data structure|data structure]], a [[Subroutine|function]], or a method, and as such, is a [[Value (computer science)|value]] in [[Memory address|memory]] referenced by an [[Identifier (computer programming)|identifier]].  In the [[Class-based programming|class-based]] [[Object-oriented programming|object-oriented programming]] paradigm, ''object'' refers to a particular [[Instance (computer science)|instance]] of a class, where the object can be a combination of variables, functions, and data structures.  In [[Relational model|relational]] [[Database|database]] management, an object can be a table or column, or an association between data and a database entity (such as relating a person's age to a specific person).<ref name=Oppel>{{cite book |first=Andy |last=Oppel |title=SQL Demystified |publisher=McGraw Hill |year=2005| page=7 |isbn=0-07-226224-9}}</ref>}}

{{term|[[Object code|object code]]}}
{{ghat|Also '''object module'''.}}
{{defn|The product of a {{gli|compiler}}.<ref>{{cite web|url=http://whatis.techtarget.com/definition/0,,sid9_gci211824,00.html|title=Compiler|publisher=TechTarget|quote=Traditionally, the output of the compilation has been called object code or sometimes an object module.|access-date=1 September 2011}}</ref> In a general sense object code is a sequence of [[Statement (computer science)|statements]] or instructions in a computer language,<ref>{{cite book|last1=Aho|first1=Alfred V.|last2=Sethi|first2=Ravi|author-link2=Ravi Sethi|last3=Ullman|first3=Jeffrey D.|author-link3=Jeffrey Ullman|title=Compilers: principles, techniques, and tools|series=Computer Science|year=1986|publisher=Mark S. Dalton|isbn=0-201-10194-7|page=704|chapter=10 Code Optimization}}</ref> usually a [[Machine code|machine code]] language (i.e., [[Binary file|binary]]) or an intermediate language such as register transfer language (RTL). The term indicates that the code is the [[Philosophy:Goal|goal]] or result of the compiling process, with some early sources referring to source code as a "subject program."}}

{{term|[[Object-oriented analysis and design|object-oriented analysis and design]] (OOAD)}}{{anchor|object-oriented analysis and design}}
{{defn|A technical approach for analyzing and designing an application, system, or business by applying {{gli|object-oriented programming}}, as well as using visual modeling throughout the software development process to guide stakeholder communication and product quality.}}

{{term|[[Object-oriented programming|object-oriented programming]] (OOP)}}{{anchor|object-oriented programming}}
{{defn|A {{gli|programming paradigm}} based on the concept of "[[Object (computer science)|objects]]", which can contain [[Data|data]], in the form of {{gli|field|fields}} (often known as ''attributes'' or ''properties''), and code, in the form of {{gli|procedure|procedures}} (often known as ''methods''). A feature of objects is an object's procedures that can access and often modify the data fields of the object with which they are associated (objects have a notion of "[[This (computer programming)|this]]" or "self"). In OOP, computer programs are designed by making them out of objects that interact with one another.<ref>{{Cite journal
  | last1 = Kindler | first1 =  E.
  | last2 = Krivy | first2 = I.
  | title = Object-Oriented Simulation of systems with sophisticated control
  | journal = International Journal of General Systems
  | year = 2011 | volume = 40
 | issue = 3
 | pages = 313–343| doi = 10.1080/03081079.2010.539975
 | s2cid = 205549734
 }}</ref><ref>{{Cite book|last1=Lewis|first1=John|last2=Loftus|first2= William|title=Java Software Solutions Foundations of Programming Design 6th ed|publisher=Pearson Education Inc.|year=2008|isbn=978-0-321-53205-3}}, section 1.6 "Object-Oriented Programming"</ref> OOP languages are diverse, but the most popular ones are [[Class-based programming|class-based]], meaning that objects are [[Instance (computer science)|instances]] of {{gli|class|classes}}, which also determine their [[Data type|types]].}}

{{term|[[Open-source software|open-source software]] (OSS)}}{{anchor|open-source software}}
{{defn|A type of {{gli|computer software}} in which {{gli|source code}} is released under a [[Open-source license|license]] in which the [[Copyright|copyright]] holder grants users the rights to study, change, and [[Software distribution|distribute the software]] to anyone and for any purpose.<ref>{{cite book|author=St. Laurent, Andrew M.|title=Understanding Open Source and Free Software Licensing|publisher=O'Reilly Media|year=2008|isbn=9780596553951|page=4|url=https://books.google.com/books?id=04jG7TTLujoC&pg=PA4}}</ref> Open-source software may be developed in a [[Open-source model|collaborative public manner]]. Open-source software is a prominent example of [[Open collaboration|open collaboration]].<ref name="Open Collaboration">{{Cite journal|last1=Levine|first1=Sheen S.|last2=Prietula|first2=Michael J.|date=2013-12-30|title=Open Collaboration for Innovation: Principles and Performance|journal=Organization Science|volume=25|issue=5|pages=1414–1433|doi=10.1287/orsc.2013.0872|issn=1047-7039|arxiv=1406.7541|s2cid=6583883}}</ref>}}

{{term|[[Operating system|operating system]] (OS)}}{{anchor|operating system}}
{{defn|[[Software:System software|System software]] that manages [[Computer hardware|computer hardware]], {{gli|software}} resources, and provides common {{gli|daemon|services}} for {{gli|computer program|computer programs}}.}}

{{term|[[Engineering:Optical fiber|optical fiber]]}}
{{defn|A flexible, [[Transparency and translucency|transparent]] [[Chemistry:Fiber|fiber]] made by [[Engineering:Drawing (manufacturing)|drawing]] [[Chemistry:Glass|glass]] ([[Chemistry:Silica|silica]]) or plastic to a diameter slightly thicker than that of a [[Hair's breadth|human hair]].<ref>{{cite web|title=Optical Fiber|url=http://www.thefoa.org/tech/ref/basic/fiber.html|website=www.thefoa.org |publisher=[[Organization:The Fiber Optic Association|The Fiber Optic Association]] |access-date=17 April 2015}}</ref> Optical fibers are used most often as a means to transmit light between the two ends of the fiber and find wide usage in [[Physics:Fiber-optic communication|fiber-optic communication]]s, where they permit transmission over longer distances and at higher [[Bandwidth (computing)|bandwidths]] (data rates) than electrical cables. Fibers are used instead of [[Chemistry:Metal|metal]] wires because signals travel along them with less [[Physics:Attenuation|loss]]; in addition, fibers are immune to [[Engineering:Electromagnetic interference|electromagnetic interference]], a problem from which metal wires suffer.<ref>{{cite book|ref=Senior|last1=Senior|first1=John M.|last2=Jamro|first2=M. Yousif|title=Optical fiber communications: principles and practice|date=2009|publisher=Pearson Education|isbn=978-0130326812|pages=7–9}}</ref>}}
{{glossaryend}}

==P==
{{glossary}}
{{term|[[Pair programming|pair programming]]}}
{{defn|An [[Agile software development|agile software development]] technique in which two programmers work together at one workstation. One, the ''driver'', writes [[Source code|code]] while the other, the ''observer'' or ''navigator'',<ref>{{cite conference |last1=Williams |first1=Laurie|title=Integrating pair programming into a software development process |pages=27–36 |doi=10.1109/CSEE.2001.913816 |conference=14th Conference on Software Engineering Education and Training |date=February 19–20, 2001 |location=Charlotte |isbn=0-7695-1059-0 |quote=One of the programmers, the driver, has control of the keyboard/mouse and actively implements the program. The other programmer, the observer, continuously observes the work of the driver to identify tactical (syntactic, spelling, etc.) defects, and also thinks strategically about the direction of the work.}}</ref> [[Code review|reviews]] each line of code as it is typed in. The two programmers switch roles frequently.}}

{{term|[[Parallel computing|parallel computing]]}}
{{defn|A type of {{gli|computation}} in which many calculations or the execution of [[Process (computing)|process]]es are carried out simultaneously.<ref>{{cite book|last=Gottlieb|first=Allan|title=Highly parallel computing|year=1989|publisher=Benjamin/Cummings|location=Redwood City, Calif.|isbn=978-0-8053-0177-9|url=http://dl.acm.org/citation.cfm?id=160438|author2=Almasi, George S.}}</ref> Large problems can often be divided into smaller ones, which can then be solved at the same time. There are several different forms of parallel computing: [[Bit-level parallelism|bit-level]], [[Instruction-level parallelism|instruction-level]], [[Data parallelism|data]], and [[Task parallelism|task parallelism]].}}

{{term|[[Parameter (computer programming)|parameter]]}}
{{ghat|Also '''formal argument'''.}}
{{defn|In {{gli|computer programming}}, a special kind of variable, used in a {{gli|subroutine}} to refer to one of the pieces of data provided as input to the subroutine.{{efn|1=In this article, the term "subroutine" refers to any subroutine-like construct, which have different names and slightly different meanings depending on the {{gli|programming language}} being discussed.}} These pieces of data are the values<ref>{{cite book|last1=Prata|first1=Stephen|title=C primer plus|date=2004|publisher=Sams|isbn=978-0-672-32696-7|pages=276–277|edition=5th}}</ref><ref>{{cite web|title=Working Draft, Standard for Programming Language C++|url=http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1905.pdf|website=www.open-std.org|access-date=1 January 2018}}</ref><ref>{{cite web|last1=Gordon|first1=Aaron|title=Subprograms and Parameter Passing|url=http://rowdysites.msudenver.edu/~gordona/cs3210/lects/lect10.html|website=rowdysites.msudenver.edu/~gordona|access-date=1 January 2018|archive-date=1 January 2018|archive-url=https://web.archive.org/web/20180101140104/http://rowdysites.msudenver.edu/~gordona/cs3210/lects/lect10.html|url-status=dead}}</ref> of the arguments (often called ''actual arguments'' or ''actual parameters'') with which the subroutine is going to be called/invoked. An ordered list of parameters is usually included in the definition of a subroutine, so that, each time the subroutine is called, its arguments for that call are evaluated, and the resulting values can be assigned to the corresponding parameters.}}

{{term|[[Engineering:Peripheral|peripheral]]}}
{{defn|Any auxiliary or ancillary device connected to or integrated within a computer system and used to send information to or retrieve information from the computer. An ''input device'' sends data or instructions to the computer; an ''output device'' provides output from the computer to the user; and an ''input/output device'' performs both functions.}}

{{term|[[Pointer (computer programming)|pointer]]}}
{{defn|Is an [[Object (computer science)|object]] in many [[Programming language|programming language]]s that stores a [[Memory address|memory address]]. This can be that of another value located in [[Computer memory|computer memory]], or in some cases, that of memory-mapped [[Computer hardware|computer hardware]]. A pointer ''references'' a location in memory, and obtaining the value stored at that location is known as ''[[Dereference operator|dereferencing]]'' the pointer. As an analogy, a page number in a book's index could be considered a pointer to the corresponding page; dereferencing such a pointer would be done by flipping to the page with the given page number and reading the text found on that page. The actual format and content of a pointer variable is dependent on the underlying [[Computer architecture|computer architecture]].}}

{{term|[[Postcondition|postcondition]]}}
{{defn|In {{gli|computer programming}}, a condition or predicate that must always be true just after the execution of some section of code or after an operation in a [[Formal specification|formal specification]]. Postconditions are sometimes tested using assertions within the code itself. Often, postconditions are simply included in the documentation of the affected section of code.}}

{{term|[[Precondition|precondition]]}}
{{defn|In {{gli|computer programming}}, a condition or predicate that must always be true just prior to the execution of some section of [[Code|code]] or before an operation in a [[Formal specification|formal specification]].  If a precondition is violated, the effect of the section of [[Code|code]] becomes undefined and thus may or may not carry out its intended work.  [[Computer security|Security]] problems can arise due to incorrect preconditions.}}

{{term|primary storage}}
{{defn|(Also known as ''main memory'', ''internal memory'' or ''prime memory''), often referred to simply as ''memory'', is the only one directly accessible to the CPU. The CPU continuously reads instructions stored there and executes them as required. Any data actively operated on is also stored there in uniform manner.}}

{{term|[[Primitive data type|primitive data type]]}}
{{defn|}}

{{term|[[Priority queue|priority queue]]}}
{{defn|An [[Abstract data type|abstract data type]] which is like a regular {{gli|queue}} or {{gli|stack}} data structure, but where additionally each element has a "priority" associated with it. In a priority queue, an element with high priority is served before an element with low priority. In some implementations, if two elements have the same priority, they are served according to the order in which they were enqueued, while in other implementations, ordering of elements with the same priority is undefined.}}

{{term|[[Procedural programming|procedural programming]]}}
{{defn|}}

{{term|procedure}}
{{defn|In [[Computer programming|computer programming]], a subroutine is a sequence of program instructions that performs a specific task, packaged as a unit. This unit can then be used in programs wherever that particular [[Task (computing)|task]] should be performed.  {{anchor|SUBROUTINE_DEFINITION}}Subroutines may be defined within programs, or separately in libraries that can be used by many programs.  In different programming languages, a subroutine may be called a routine, subprogram, function, method, or procedure. Technically, these terms all have different definitions. The generic, umbrella term  callable unit is sometimes used.<ref name="U.S. Election Assistance Commission 2007">{{cite web
 |author      = U.S. Election Assistance Commission
 |title       = Definitions of Words with Special Meanings
 |work        = Voluntary Voting System Guidelines
 |year        = 2007
 |url         = http://www.eac.gov/vvsg/glossary.aspx
 |access-date  = 2013-01-14
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20121208084203/http://www.eac.gov/vvsg/glossary.aspx
 |archive-date = 2012-12-08
}}</ref>}}

{{term|[[Program lifecycle phase|program lifecycle phase]]}}
{{defn|Program lifecycle phases are the stages a {{gli|computer program}} undergoes, from initial creation to deployment and [[Execution (computing)|execution]]. The phases are edit time, compile time, link time, distribution time, installation time, load time, and run time.}}

{{term|[[Programming language|programming language]]}}
{{defn|A [[Formal language|formal language]], which comprises a set of instructions that produce various kinds of output. Programming languages are used in {{gli|computer programming}} to implement {{gli|algorithm|algorithms}}.}}

{{term|[[Programming language implementation|programming language implementation]]}}
{{defn|Is a system for executing computer programs. There are two general approaches to programming language implementation: [[Interpreter (computing)|interpretation]] and [[Compiler|compilation]].<ref name="RantaBook">{{cite book |last1=Ranta |first1=Aarne |title=Implementing Programming Languages |date=9 May 2012 |publisher=College Publications |isbn=9781848900646 |pages=16–18 |url=http://www.cse.chalmers.se/edu/year/2012/course/DAT150/lectures/plt-book.pdf#page=16 |access-date=22 March 2020}}</ref>}}

{{term|[[Programming language theory|programming language theory]]}}
{{defn|(PLT) is a branch of [[Computer science|computer science]] that deals with the design, implementation, analysis, characterization, and classification of [[Programming language|programming language]]s and of their individual [[Programming language#Elements|features]].  It falls within the discipline of computer science, both depending on and affecting [[Mathematics|mathematics]], [[Software engineering|software engineering]], [[Social:Linguistics|linguistics]] and even [[Cognitive science|cognitive science]].  It has become a well-recognized branch of computer science, and an active research area, with results published in numerous [[Academic journal|journals]] dedicated to PLT, as well as in general computer science and engineering publications.}}

{{term|[[Prolog]]}}
{{defn|Is a [[Logic programming|logic programming]] language associated with [[Artificial intelligence|artificial intelligence]] and [[Computational linguistics|computational linguistics]].<ref name=Clocksin2003>{{Cite book  | last1 = Clocksin | first1 = William F. | last2 = Mellish | first2 = Christopher S. | title = Programming in Prolog | year = 2003 | publisher = Springer-Verlag | location = Berlin ; New York | isbn = 978-3-540-00678-7 }}</ref><ref name=Bratko2012>{{Cite book  | last1 = Bratko | first1 = Ivan | title = Prolog programming for artificial intelligence |edition = 4th | year = 2012 | publisher = Addison Wesley | location = Harlow, England ; New York | isbn = 978-0-321-41746-6 }}</ref><ref name=Covington1994>{{Cite book  | last1 = Covington | first1 = Michael A. | title = Natural language processing for Prolog programmers | year = 1994 | publisher = Prentice Hall | location = Englewood Cliffs, N.J. | isbn = 978-0-13-629213-5 }}</ref>  Prolog has its roots in [[First-order logic|first-order logic]], a formal logic, and unlike many other [[Programming language|programming language]]s, Prolog is intended primarily as a [[Declarative programming|declarative programming]] language: the program logic is expressed in terms of [[Finitary relation|relations]], represented as facts and [[Rule of inference|rules]].  A [[Computation|computation]] is initiated by running a ''query'' over these relations.<ref>Lloyd, J. W. (1984). Foundations of logic programming. Berlin: Springer-Verlag. {{ISBN|978-3-540-13299-8}}.</ref>}}

{{term|[[Python (programming language)|Python]]}}
{{defn|Is an [[Interpreted language|interpreted]], [[High-level programming language|high-level]] and [[General-purpose programming language|general-purpose programming language]]. Created by [[Biography:Guido van Rossum|Guido van Rossum]] and first released in 1991, Python's design philosophy emphasizes code readability with its notable use of [[Off-side rule|significant whitespace]]. Its [[Language construct|language construct]]s and [[Object-oriented programming|object-oriented]] approach aim to help programmers write clear, logical code for small and large-scale projects.<ref>Kuhlman, Dave. "A Python Book: Beginning Python, Advanced Python, and Python Exercises". Section 1.1. Archived from the original (PDF) on 23 June 2012.</ref>}}
{{glossaryend}}

==Q==
{{glossary}}
{{term|[[Quantum computing|quantum computing]]}}
{{defn|The use of [[Physics:Quantum mechanics|quantum-mechanical]] phenomena such as [[Physics:Quantum superposition|superposition]] and [[Quantum entanglement|entanglement]] to perform {{gli|computation}}. A quantum computer is used to perform such computation, which can be implemented theoretically or physically.<ref name=2018Report>{{cite book | title=Quantum Computing : Progress and Prospects (2018) | page= I-5 | publisher=National Academies Press | editor-last1 = Grumbling | editor-first1 = Emily | editor-last2 = Horowitz | editor-first2 = Mark | author= ((The National Academies of Sciences, Engineering, and Medicine)) |location=Washington, D.C. | year=2019 | doi=10.17226/25196|isbn=978-0-309-47969-1 | s2cid= 125635007 | oclc=1081001288 }}</ref>{{rp|I-5}}}}

{{term|[[Queue (abstract data type)|queue]]}}
{{defn|A {{gli|collection}} in which the entities in the collection are kept in order and the principal (or only) operations on the collection are the addition of entities to the rear terminal position, known as ''enqueue'', and removal of entities from the front terminal position, known as ''dequeue''.}}

{{term|[[Quicksort|quicksort]]}}
{{ghat|Also '''partition-exchange sort'''.}}
{{defn|An efficient [[Sorting algorithm|sorting algorithm]] which serves as a systematic method for placing the elements of a [[Random access|random access]] [[Computer file|file]] or an [[Array data structure|array]] in order.}}
{{glossaryend}}

==R==
{{glossary}}
{{term|[[R (programming language)|R programming language]]}}
{{defn|'''R''' is a [[Programming language|programming language]] and [[Free software|free software]] environment for statistical computing and graphics supported by the R Foundation for Statistical Computing.{{refn | R language and environment
* {{Cite web |url=https://cran.r-project.org/doc/FAQ/R-FAQ.html#What-is-R_003f |title=R FAQ| at=2.1 What is R? |date=2017-10-04 |first=Kurt |last=Hornik |website=The Comprehensive R Archive Network |access-date=2018-08-06}}
R Foundation
* {{Cite web |url=https://cran.r-project.org/doc/FAQ/R-FAQ.html#What-is-the-R-Foundation_003f |title=R FAQ |at=2.13 What is the R Foundation? |date=2017-10-04 |first=Kurt |last=Hornik |website=The Comprehensive R Archive Network |access-date=2018-08-06}}
The R Core Team [https://cran.r-project.org/doc/FAQ/R-FAQ.html#Citing-R asks authors who use R in their data analysis] to cite the software using:
* R Core Team (2016). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL http://www.R-project.org/.
}} The R language is widely used among [[Statistician|statistician]]s and [[Data mining|data miners]] for developing statistical software{{refn | widely used
* {{cite web |author1=Fox, John  |author2=Andersen, Robert  |name-list-style=amp | title = Using the R Statistical Computing Environment to Teach Social Statistics Courses | publisher = Department of Sociology, McMaster University | date = January 2005 | url = https://socialsciences.mcmaster.ca/jfox/Teaching-with-R.pdf | access-date = 2018-08-06 }}
* {{cite news | url=https://www.nytimes.com/2009/01/07/technology/business-computing/07program.html |title=Data Analysts Captivated by R's Power | date=2009-01-06 | access-date=2018-08-06|last=Vance| first=Ashlee |work={{wipe|New York Times}}| quote=R is also the name of a popular programming language used by a growing number of data analysts inside corporations and academia. It is becoming their lingua franca...}}
}} and [[Data analysis|data analysis]].<ref>{{cite news | url=https://www.nytimes.com/2009/01/07/technology/business-computing/07program.html |title=Data Analysts Captivated by R's Power | date=2009-01-06 | access-date=2018-08-06|last=Vance| first=Ashlee |work={{wipe|New York Times}}| quote=R is also the name of a popular programming language used by a growing number of data analysts inside corporations and academia. It is becoming their lingua franca...}}</ref>}}

{{term|[[Radix|radix]]}}
{{ghat|Also '''base'''.}}
{{defn|In [[Numeral system|digital numeral systems]], the number of unique [[Numerical digit|digits]], including the digit zero, used to represent numbers in a [[Positional notation|positional]] numeral system. For example, in the decimal/denary system (the most common system in use today) the radix (base number) is ten, because it uses the ten digits from 0 through 9, and all other numbers are uniquely specified by positional combinations of these ten base digits; in the {{gli|binary number|binary system}} that is the standard in {{gli|computing}}, the radix is two, because it uses only two digits, 0 and 1, to uniquely specify each number.}}

{{term|[[Record (computer science)|record]]}}
{{defn|A record (also called a structure,  [[Struct (C programming language)|struct]], or compound data) is a basic [[Data structure|data structure]]. Records in a [[Database|database]] or [[Engineering:Spreadsheet|spreadsheet]] are usually called "[[Software:Row (database)|row]]s".<ref>{{cite web|title=Computer Science Dictionary Definitions|url=http://www.computingstudents.com/dictionary/?word=Record|website=Computing Students|access-date=Jan 22, 2018}}</ref><ref name="Radványi">{{cite book |last1=Radványi |first1=Tibor |title=Database Management Systems |date=2014 |publisher=Eszterházy Károly College |page=19 |url=https://www.tankonyvtar.hu/en/tartalom/tamop412A/2011-0038_49_radvanyi_en/index.html |access-date=23 September 2018}}</ref><ref name="Kahate">{{cite book |last1=Kahate |first1=Atul |title=Introduction to Database Management Systems |date=2006 |publisher=Pearson |isbn=978-81-317-0078-5 |page=3 |url=https://books.google.com/books?id=mxYESolfLfoC |access-date=23 September 2018}}</ref><ref>{{cite book |last1=Connolly |first1=Thomas |title=Database Solutions: A Step by Step Guide to Building Databases |url=https://archive.org/details/databasesolution00conn_535 |url-access=registration |date=2004 |publisher=Pearson |isbn=978-0-321-17350-8 |page=[https://archive.org/details/databasesolution00conn_535/page/n19 7] |edition=2nd }}</ref>}}

{{term|[[Recursion|recursion]]}}
{{defn|Occurs when a thing is defined in terms of itself or of its type. Recursion is used in a variety of disciplines ranging from [[Social:Linguistics|linguistics]] to [[Logic|logic]]. The most common application of recursion is in [[Mathematics|mathematics]] and {{gli|computer science}}, where a [[Function (mathematics)|function]] being defined is applied within its own definition. While this apparently defines an infinite number of instances (function values), it is often done in such a way that no infinite loop or infinite chain of references can occur.}}

{{term|[[Reference (computer science)|reference]]}}
{{defn|Is a value that enables a program to indirectly access a particular datum, such as a [[Variable (computer science)|variable]]'s value or a [[Record (computer science)|record]], in the [[Computer|computer]]'s memory or in some other [[Engineering:Data storage device|storage device]].  The reference is said to refer to the datum, and accessing the datum is called [[Dereference operator|dereferencing]] the reference.}}

{{term|[[Reference counting|reference counting]]}}
{{defn|A programming technique of storing the number of {{gli|reference|references}}, {{gli|pointer|pointers}}, or {{gli|handle|handles}} to a resource, such as an object, a block of memory, disk space, and others. In [[Garbage collection (computer science)|garbage collection]] algorithms, reference counts may be used to deallocate objects which are no longer needed.}}

{{term|[[Relational database|relational database]]}}
{{defn|Is a digital [[Database|database]] based on the [[Relational model|relational model]] of data, as proposed by E. F. Codd in 1970.<ref>Codd, E. F. (1970). "A Relational Model of Data for Large Shared Data Banks". Communications of the ACM. 13 (6): 377–387. doi:10.1145/362384.362685.</ref>
A software system used to maintain relational databases is a [[Software:Relational database management system|relational database management system]] (RDBMS). Many relational database systems have an option of using the [[SQL]] (Structured Query Language) for querying and maintaining the database.<ref>{{cite web |last=Ambler |first=Scott |title=Relational Databases 101: Looking at the Whole Picture |url=http://www.agiledata.org/essays/relationalDatabases.html }}</ref>{{better source needed|date=June 2018}}}}

{{term|[[Reliability engineering|reliability engineering]]}}
{{defn|A sub-discipline of [[Engineering:Systems engineering|systems engineering]] that emphasizes dependability in the lifecycle management of a product. Reliability describes the ability of a system or component to function under stated conditions for a specified period of time.<ref>Institute of Electrical and Electronics Engineers (1990) IEEE Standard Computer Dictionary: A Compilation of IEEE Standard Computer Glossaries. New York, NY {{ISBN|1-55937-079-3}}</ref> Reliability is closely related to [[Availability|availability]], which is typically described as the ability of a component or system to function at a specified moment or interval of time.}}

{{term|[[Regression testing|regression testing]]}}
{{defn|(rarely ''non-regression testing''<ref>{{cite book |last1=Pezzè |first1=Mauro |last2=Young |first2=Michal |title=Software testing and analysis: process, principles, and techniques |date=2008 |publisher=Wiley |url=https://www.google.com/search?q=Mauro+%22non-regression%22+%22regression+testing%22 |quote=Testing activities that focus on regression problems are called (non) regression testing. Usually "non" is omitted}}</ref>) is re-running [[Functional testing|functional]] and [[Non-functional testing|non-functional tests]] to ensure that previously developed and tested software still performs after a change.<ref>{{cite book|last=Basu|first=Anirban| title=Software Quality Assurance, Testing and Metrics| year=2015| publisher=PHI Learning| isbn=978-81-203-5068-7| url=https://books.google.com/books?id=aNTiCQAAQBAJ&pg=PA150}}</ref> If not, that would be called a ''[[Software regression|regression]]''. Changes that may require regression testing include [[Software bug|bug]] fixes, software enhancements, [[Configuration file|configuration]] changes, and even substitution of [[Engineering:Electronic component|electronic component]]s.<ref>[[Organization:National Academies of Sciences, Engineering, and Medicine|National Research Council]] Committee on Aging Avionics in Military Aircraft: [https://www.nap.edu/catalog/10108/aging-avionics-in-military-aircraft ''Aging Avionics in Military Aircraft'']. The National Academies Press, 2001, page 2: ″Each technology-refresh cycle requires regression testing.″</ref> As regression test suites tend to grow with each found defect, test automation is frequently involved. Sometimes a [[Social:Change impact analysis|change impact analysis]] is performed to determine an appropriate subset of tests (''non-regression analysis''<ref>{{cite book |last1=Boulanger |first1=Jean-Louis |title=CENELEC 50128 and IEC 62279 Standards |date=2015 |publisher=Wiley |isbn=978-1119122487 |url=https://books.google.com/books?id=IbZNCAAAQBAJ&pg=PA149}}</ref>).}}

{{term|[[Requirements analysis|requirements analysis]]}}
{{defn|In [[Engineering:Systems engineering|systems engineering]] and [[Software engineering|software engineering]], requirements analysis focuses on the tasks that determine the needs or conditions to meet the new or altered product or project, taking account of the possibly conflicting [[Requirement|requirement]]s of the various [[Social:Stakeholder (corporate)|stakeholders]], ''analyzing, documenting, validating and managing'' software or system requirements.<ref>{{cite book|isbn=9780471972082|title=Requirements Engineering: Processes and Techniques|url=https://archive.org/details/requirementsengi1998koto|url-access=registration|last1=Kotonya|first1=Gerald|last2=Sommerville|first2=Ian|year=1998|location=Chichester, UK|publisher=John Wiley and Sons}}</ref>}}

{{term|robotics}}
{{defn|An interdisciplinary branch of [[Engineering:List of engineering branches|engineering]] and science that includes [[Engineering:Mechanical engineering|mechanical engineering]], [[Electronic engineering|electronic engineering]], [[Information engineering (field)|information engineering]], {{gli|computer science}}, and others. Robotics involves design, construction, operation, and use of [[Engineering:Robot|robot]]s, as well as computer systems for their perception, control, sensory feedback, and [[Data processing|information processing]]. The goal of robotics is to design intelligent machines that can help and assist humans in their day-to-day lives and keep everyone safe.}}

{{term|[[Round-off error|round-off error]]}}
{{ghat|Also '''rounding error'''.<ref>{{citation |title=Numerical Computation 1: Methods, Software, and Analysis |author-first=Christoph W. |author-last=Ueberhuber |publisher=Springer |date=1997 |isbn=978-3-54062058-7 |url=https://books.google.com/books?id=JH9I7EJh3JUC&pg=PA139 |pages=139–146}}</ref>}}
{{defn|The difference between the result produced by a given {{gli|algorithm}} using exact arithmetic and the result produced by the same algorithm using finite-precision, rounded arithmetic.<ref name="Forrester_2018">{{cite book |title= Math/Comp241 Numerical Methods (lecture notes) |author-first=Dick |author-last=Forrester |publisher=[[Organization:Dickinson College|Dickinson College]] |date=2018}}</ref> Rounding errors are due to inexactness in the representation of real numbers and the arithmetic operations done with them. This is a form of quantization error.<ref>{{citation |title=Information Technology in Theory |author-first1=Pelin |author-last1=Aksoy |author-first2=Laura |author-last2=DeNardis |publisher=Cengage Learning |date=2007 |isbn=978-1-42390140-2 |page=134 |url=https://books.google.com/books?id=KGS5IcixljwC&pg=PA134}}</ref> When using approximation [[Equation|equation]]s or algorithms, especially when using finitely many digits to represent real numbers (which in theory have infinitely many digits), one of the goals of [[Numerical analysis|numerical analysis]] is to [[Error analysis (mathematics)|estimate]] computation errors.<ref>{{citation |title=A First Course in Numerical Analysis |edition=2nd |series=Dover Books on Mathematics |author-first1=Anthony |author-last1=Ralston |author-first2=Philip |author-last2=Rabinowitz |publisher=Courier Dover Publications |date=2012 |isbn=978-0-48614029-2 |url=https://books.google.com/books?id=TVq8AQAAQBAJ&pg=PA2 |pages=2–4}}</ref> Computation errors, also called [[Numerical error|numerical error]]s, include both [[Truncation error|truncation error]]s and roundoff errors.<ref>{{citation |title=Introduction to Numerical Analysis Using MATLAB |author-first=Rizwan |author-last=Butt |publisher=Jones & Bartlett Learning |date=2009 |isbn=978-0-76377376-2 |pages=11–18 |url=https://books.google.com/books?id=QWub-UVGxqkC&pg=PA11}}</ref>}}

{{term|[[Engineering:Router (computing)|router]]}}
{{defn|A networking device that forwards data packets between [[Computer network|computer network]]s. Routers perform the traffic directing functions on the [[Internet]].  Data sent through the internet, such as a [[Web page|web page]] or [[Email|email]], is in the form of data packets.   A packet is typically [[Packet forwarding|forwarded]] from one router to another router through the networks that constitute an internetwork (e.g. the Internet) until it reaches its destination [[Node (networking)|node]].<ref>{{cite web|url=http://www.tcpipguide.com/free/t_OverviewOfKeyRoutingProtocolConceptsArchitecturesP.htm|title=Overview Of Key Routing Protocol Concepts: Architectures, Protocol Types, Algorithms and Metrics|publisher=Tcpipguide.com|access-date=15 January 2011|url-status=live|archive-url=https://web.archive.org/web/20101220111345/http://tcpipguide.com/free/t_OverviewOfKeyRoutingProtocolConceptsArchitecturesP.htm|archive-date=20 December 2010}}</ref>}}

{{term|[[Routing table|routing table]]}}
{{defn|In computer networking a routing table, or routing information base (RIB), is a data table stored in a [[Engineering:Router (computing)|router]] or a network host that lists the routes to particular network destinations, and in some cases, [[Metrics (networking)|metrics]] (distances) associated with those routes. The routing table contains information about the [[Network topology|topology of the network]] immediately around it.}}

{{term|[[Run time (program lifecycle phase)|run time]]}}
{{defn|Runtime, run time, or execution time is the final phase of a [[Computer program|computer program]]{{'}}s [[Program lifecycle phase|life cycle]], in which the code is being [[Execution (computing)|executed]] on the computer's [[Central processing unit|central processing unit]] (CPU) as [[Machine code|machine code]]. In other words, "runtime" is the running phase of a program.}}

{{term|[[Run time (program lifecycle phase)|run time error]]}}
{{defn|A [[Runtime error detection|runtime error]] is detected after or during the execution (running state) of a program, whereas a [[Compile time|compile-time]] error is detected by the [[Compiler|compiler]] before the program is ever executed. Type checking, [[Register allocation|register allocation]], [[Code generation (compiler)|code generation]], and code optimization are typically done at compile time, but may be done at runtime depending on the particular language and compiler. Many other runtime errors exist and are handled differently by different [[Programming language|programming language]]s, such as [[Division by zero|division by zero]] errors, domain errors, [[Bounds checking|array subscript out of bounds]] errors, [[Arithmetic underflow|arithmetic underflow]] errors, several types of underflow and overflow errors, and many other runtime errors generally considered as software bugs which may or may not be caught and handled by any particular computer language.}}
{{glossaryend}}

==S==
{{glossary}}
{{term|[[Search algorithm|search algorithm]]}}
{{defn|Any {{gli|algorithm}} which solves the [[Search problem|search problem]], namely, to retrieve information stored within some data structure, or calculated in the [[Feasible region|search space]] of a problem {{gli|domain}}, either with [[Continuous or discrete variable|discrete or continuous values]].}}

{{term|[[Auxiliary memory|secondary storage]]}}
{{defn|Also known as ''external memory'' or ''auxiliary storage'', differs from primary storage in that it is not directly accessible by the CPU. The computer usually uses its [[Input output|input/output]] channels to access secondary storage and transfer the desired data to primary storage. Secondary storage is non-volatile (retaining data when power is shut off). Modern computer systems typically have two orders of magnitude more secondary storage than primary storage because secondary storage is less expensive.
}}

{{term|[[Selection sort|selection sort]]}}
{{defn|Is an [[In-place algorithm|in-place]] [[Comparison sort|comparison]] [[Sorting algorithm|sorting algorithm]]. It has an [[Big O notation|O]](''n''<sup>2</sup>) [[Time complexity|time complexity]], which makes it inefficient on large lists, and generally performs worse than the similar [[Insertion sort|insertion sort]]. Selection sort is noted for its simplicity and has performance advantages over more complicated algorithms in certain situations, particularly where [[Auxiliary memory|auxiliary memory]] is limited.}}

{{term|[[Semantics (computer science)|semantics]]}}
{{defn|In [[Programming language theory|programming language theory]], semantics is the field concerned with the rigorous mathematical study of the meaning of [[Programming language|programming language]]s. It does so by evaluating the meaning of syntactically valid [[String (computer science)|strings]] defined by a specific programming language, showing the computation involved. In such a case that the evaluation would be of syntactically invalid strings, the result would be non-computation. Semantics describes the processes a computer follows when executing a program in that specific language. This can be shown by describing the relationship between the input and output of a program, or an explanation of how the program will be executed on a certain platform, hence creating a [[Model of computation|model of computation]].}}

{{term|[[Sequence|sequence]]}}
{{defn|In [[Mathematics|mathematics]], a sequence is an enumerated collection of objects in which repetitions are allowed and [[Order theory|order]] does matter.  Like a [[Set (mathematics)|set]], it contains [[Element (mathematics)|members]] (also called ''elements'', or ''terms'').  The number of elements (possibly infinite) is called the ''length'' of the sequence.  Unlike a set, the same elements can appear multiple times at different positions in a sequence, and order does matter.  Formally, a sequence can be defined as a [[Function (mathematics)|function]] whose domain is either the set of the [[Natural number|natural number]]s (for infinite sequences) or the set of the first ''n'' natural numbers (for a sequence of finite length ''n'').

The position of an element in a sequence is its ''rank'' or ''index''; it is the natural number for which the element is the image. The first element has index 0 or 1, depending on the context or a specific convention.  When a symbol is used to denote a sequence, the ''n''th element of the sequence is denoted by this symbol with ''n'' as subscript; for example, the ''n''th element of the [[Fibonacci sequence]] ''F'' is generally denoted ''F''<sub>''n''</sub>.

For example, (M, A, R, Y) is a sequence of letters with the letter 'M' first and 'Y' last.  This sequence differs from (A, R, M, Y).  Also, the sequence (1, 1, 2, 3, 5, 8), which contains the number 1 at two different positions, is a valid sequence.  Sequences can be ''[[Finite set|finite]]'', as in these examples, or ''[[Infinite set|infinite]]'', such as the sequence of all even positive integers (2, 4, 6, ...).  In [[Computing|computing]] and [[Computer science|computer science]], finite sequences are sometimes called [[String (computer science)|strings]], words or lists, the different names commonly corresponding to different ways to represent them in [[Computer memory|computer memory]]; infinite sequences are called [[Stream (computing)|streams]].  The empty sequence&nbsp;(&nbsp;) is included in most notions of sequence, but may be excluded depending on the context.}}

{{term|[[Serializability|serializability]]}}
{{defn|In [[Concurrency control|concurrency control]] of [[Database|database]]s,<ref name=Bernstein87>[[Biography:Phil Bernstein|Philip A. Bernstein]], Vassos Hadzilacos, Nathan Goodman (1987): [http://research.microsoft.com/en-us/people/philbe/ccontrol.aspx ''Concurrency Control and Recovery in Database Systems''] (free PDF download), Addison Wesley Publishing Company, {{ISBN|0-201-10715-5}}</ref><ref name=Weikum01>Gerhard Weikum, Gottfried Vossen (2001): [http://www.elsevier.com/wps/find/bookdescription.cws_home/677937/description#description ''Transactional Information Systems''], Elsevier, {{ISBN|1-55860-508-8}}</ref> [[Transaction processing|transaction processing]] (transaction management), and various [[Database transaction|transactional]] applications (e.g., [[Transactional memory|transactional memory]]<ref name=Herlihy1993>[[Biography:Maurice Herlihy|Maurice Herlihy]] and J. Eliot B. Moss. ''Transactional memory: architectural support for lock-free data structures.'' Proceedings of the 20th annual international symposium on Computer architecture (ISCA '93). Volume 21, Issue 2, May 1993.</ref> and [[Software transactional memory|software transactional memory]]), both centralized and [[Distributed computing|distributed]], a [[Database transaction schedule|transaction schedule]] is '''serializable''' if its outcome (e.g., the resulting database state) is equal to the outcome of its transactions executed serially, i.e. without overlapping in time. Transactions are normally executed concurrently (they overlap), since this is the most efficient way. Serializability is the major correctness criterion for concurrent transactions' executions . It is considered the highest level of isolation between [[Database transaction|transactions]], and plays an essential role in [[Concurrency control|concurrency control]]. As such it is supported in all general purpose database systems. ''[[Two-phase locking|Strong strict two-phase locking]]'' (SS2PL) is a popular serializability mechanism utilized in most of the database systems (in various variants) since their early days in the 1970s.
}}

{{term|[[Serialization|serialization]]}}
{{defn|Is the process of translating [[Data structure|data structure]]s or [[Object (computer science)|object]] state into a format that can be stored (for example, in a [[Computer file|file]] or memory [[Data buffer|buffer]]) or transmitted (for example, across a [[Computer network|network]] connection link) and reconstructed later (possibly in a different computer environment).<ref>{{ cite web
 | author       = Marshall Cline
 | url          = http://www.parashift.com/c++-faq-lite/serialize-overview.html
 | title        = C++ FAQ: "What's this "serialization" thing all about?"
 | archive-url  = https://web.archive.org/web/20150405013606/http://isocpp.org/wiki/faq/serialization
 | archive-date = 2015-04-05
 | quote = It lets you take an object or group of objects, put them on a disk or send them through a wire or wireless transport mechanism, then later, perhaps on another computer, reverse the process, resurrecting the original object(s). The basic mechanisms are to flatten object(s) into a one-dimensional stream of bits, and to turn that stream of bits back into the original object(s).}}</ref> When the resulting series of bits is reread according to the serialization format, it can be used to create a semantically identical clone of the original object. For many complex objects, such as those that make extensive use of [[Reference (computer science)|references]], this process is not straightforward. Serialization of object-oriented [[Object (computer science)|object]]s does not include any of their associated methods with which they were previously linked.

This process of serializing an object is also called [[Marshalling (computer science)|marshalling]] an object in some situations.[http://www.ruby-doc.org/core/classes/Marshal.html][http://caml.inria.fr/pub/docs/manual-ocaml/libref/Marshal.html] The opposite operation, extracting a data structure from a series of bytes, is '''deserialization''', (also called '''unserialization''' or '''[[Unmarshalling|unmarshalling]]''').}}

{{term|service level agreement}}
{{defn|(SLA), is a commitment between a service provider and a client. Particular aspects of the service&nbsp;– quality, availability, responsibilities&nbsp;– are agreed between the service provider and the service user.<ref name="KearneyServ11">{{cite book |url=https://books.google.com/books?id=z306GUfFL5gC |chapter=The SLA Model |title=Service Level Agreements for Cloud Computing |author1=Kearney, K.T. |author2=Torelli, F. |editor1=Wieder, P. |editor2=Butler, J.M. |editor3=Theilmann, W. |editor4=Yahyapour, R.  |publisher=Springer Science+Business Media, LLC |pages=43–68 |year=2011 |isbn=9781461416142}}</ref> The most common component of an SLA is that the services should be provided to the customer as agreed upon in the contract. As an example, Internet service providers and [[Company:Telephone company|telcos]] will commonly include service level agreements within the terms of their contracts with customers to define the level(s) of service being sold in plain language terms. In this case the SLA will typically have a technical definition in  ''[[Mean time between failures|mean time between failures]]'' (MTBF), ''[[Engineering:Mean time to repair|mean time to repair]]'' or ''[[Engineering:Mean time to recovery|mean time to recovery]]'' (MTTR); identifying which party is responsible for reporting faults or paying fees; responsibility for various data rates; [[Throughput|throughput]]; [[Jitter|jitter]]; or similar measurable details.}}

{{term|[[Set (abstract data type)|set]]}}
{{defn|Is an [[Abstract data type|abstract data type]] that can store unique values, without any particular [[Sequence|order]]. It is a computer implementation of the [[Mathematics|mathematical]] concept of a [[Finite set|finite set]]. Unlike most other [[Collection (abstract data type)|collection]] types, rather than retrieving a specific element from a set, one typically tests a value for membership in a set.}}

{{term|singleton variable}}
{{defn|A variable that is referenced only once. May be used as a dummy argument in a function call, or when its address is assigned to another variable which subsequently accesses its allocated storage. Singleton variables sometimes occur because a mistake has been made – such as assigning a value to a variable and forgetting to use it later, or mistyping one instance of the variable name. Some compilers and lint-like tools flag occurrences of singleton variables.}}

{{term|'''soft computing'''}}
{{defn|}}

{{term|[[Software|software]]}}
{{defn|Computer software, or simply software, is a collection of [[Data (computing)|data]] or [[Computer|computer]] instructions that tell the computer how to work. This is in contrast to [[Computer hardware|physical hardware]], from which the system is built and actually performs the work. In [[Computer science|computer science]] and [[Software engineering|software engineering]], computer software is all [[Information|information]] processed by computer systems, [[Computer program|program]]s and [[Data|data]]. Computer software includes [[Computer program|computer program]]s, [[Library (computing)|libraries]] and related non-executable [[Data (computing)|data]], such as [[Software documentation|online documentation]] or [[Digital media|digital media]]. Computer hardware and software require each other and neither can be realistically used on its own.}}

{{term|[[Software agent|software agent]]}}
{{defn|Is a computer program that acts for a user or other program in a relationship of agency, which derives from the Latin ''agere'' (to do): an agreement to act on one's behalf. Such "action on behalf of" implies the [[Philosophy:Authority|authority]] to decide which, if any, action is appropriate.<ref>{{cite journal
 | last1         = Nwana
 | first1        = H.&nbsp;S.
 | year          = 1996
 | title         = Software Agents: An Overview
 | volume        = 21
 | number        = 3
 | pages         = 205–244
 | journal       = Knowledge Engineering Review
 | doi=10.1017/s026988890000789x
 | citeseerx        = 10.1.1.50.660
 | s2cid = 7839197
 }}</ref><ref>{{cite book
 | last1         = Schermer
 | first1        = B.&nbsp;W.
 | year          = 2007
 | title         = Software agents, surveillance, and the right to privacy: A legislative framework for agent-enabled surveillance
 | volume        = 21
 | number        = 3
 | pages         = 140, 205–244
 | publisher     = Leiden University Press
 | format        = paperback
 | isbn          = 978-0-596-00712-6
 | access-date    = 2012-10-30
 | url           = https://openaccess.leidenuniv.nl/handle/1887/11951
 | hdl          = 1887/11951}}</ref> Agents are colloquially known as ''bots'', from ''[[Engineering:Robot|robot]]''. They may be embodied, as when execution is paired with a robot body, or  as software such as a chatbot
executing on a phone (e.g. [[Software:Siri|Siri]])  or other computing device.  Software agents may be autonomous or work together with other agents or people.  Software agents interacting with people (e.g. chatbots, human-robot interaction environments) may possess human-like qualities such as natural language understanding and speech, personality or embody humanoid form (see Asimo).}}

{{term|[[Software construction|software construction]]}}
{{defn|Is a [[Software engineering|software engineering]] discipline. It is the detailed creation of working meaningful [[Software|software]] through a combination of coding, [[Software verification|verification]], [[Unit testing|unit testing]], [[Integration testing|integration testing]], and [[Debugging|debugging]]. It is linked to all the other [[Software engineering|software engineering]] disciplines, most strongly to [[Software design|software design]] and [[Software testing|software testing]].<ref name="SWEBOK">[[Software:Software Engineering Body of Knowledge|SWEBOK]] {{Cite book | editor = Pierre Bourque | editor2 = Robert Dupuis | editor3 = Alain Abran | editor4 = James W. Moore | title = Guide to the Software Engineering Body of Knowledge | publisher = [[Organization:IEEE Computer Society|IEEE Computer Society]] | year = 2004 | chapter = Chapter 4: Software Construction | pages = 4–1–4–5 | isbn = 0-7695-2330-7 | url = http://www.computer.org/portal/web/swebok/html/ch4#Ref2 | access-date = 2020-06-21 | archive-date = 2014-07-14 | archive-url = https://web.archive.org/web/20140714183208/http://www.computer.org/portal/web/swebok/html/ch4#Ref2 | url-status = dead }}</ref>}}

{{term|[[Software deployment|software deployment]]}}
{{defn|defn=Is all of the activities that make a [[Software system|software system]] available for use.<ref>Roger S. Pressman Software engineering: a practitioner's approach (eighth edition)</ref>}}

{{term|[[Software design|software design]]}}
{{defn|defn=Is the process by which an [[Philosophy:Agency|agent]] creates a specification of a [[Software:Artifact (software development)|software artifact]], intended to accomplish [[Philosophy:Goal|goal]]s, using a set of primitive components and subject to [[Constraint (mathematics)|constraint]]s.<ref>Ralph, P. and Wand, Y. (2009). A proposal for a formal definition of the design concept. In Lyytinen, K., Loucopoulos, P., Mylopoulos, J., and Robinson, W., editors, Design Requirements Workshop (LNBIP 14), pp. 103–136. Springer-Verlag, p. 109 {{doi|10.1007/978-3-540-92966-6_6}}.</ref> Software design may refer to either "all the activity involved in conceptualizing, framing, implementing, commissioning, and ultimately modifying complex systems" or "the activity following [[Software requirements|requirements]] specification and before [[Computer programming|programming]], as ... [in] a stylized software engineering process."<ref>{{cite journal|last=Freeman|first=Peter|author2=David Hart |s2cid=14331332|title=A Science of design for software-intensive systems|journal=Communications of the ACM|year=2004|volume=47|issue=8|pages=19–21 [20]|doi=10.1145/1012037.1012054}}</ref>}}

{{term|[[Software development|software development]]}}
{{defn|defn=Is the process of conceiving, specifying, designing, [[Computer programming|programming]], [[Software documentation|documenting]], [[Software testing|testing]], and bug fixing involved in creating and maintaining applications, [[Software framework|frameworks]], or other software components. Software development is a process of writing and [[Software maintenance|maintaining]] the [[Source code|source code]], but in a broader sense, it includes all that is involved between the conception of the desired software through to the final manifestation of the software, sometimes in a planned and [[Software development process|structured]] process.<ref>{{cite web|url=http://www.bestpricecomputers.co.uk/glossary/application-development.htm |title=Application Development (AppDev) Defined and Explained |publisher=Bestpricecomputers.co.uk |date=2007-08-13 |access-date=2012-08-05}}</ref> Therefore, software development may include research, new development, prototyping, modification, reuse, re-engineering, maintenance, or any other activities that result in software products.<ref>{{cite web|author=DRM Associates|title=New Product Development Glossary |url=http://www.npd-solutions.com/glossary.html |year=2002|access-date=2006-10-29}}</ref>}}

{{term|[[Software development process|software development process]]}}
{{defn|In [[Software engineering|software engineering]], a software development process is the process of dividing [[Software development|software development]] work into distinct phases to improve [[Software design|design]], [[Software product management|product management]], and [[Software project management|project management]].  It is also known as a software development life cycle (SDLC).  The methodology may include the pre-definition of specific deliverables and artifacts that are created and completed by a project team to develop or maintain an application.<ref name="Medicare 2008">Centers for Medicare & Medicaid Services (CMS) Office of Information Service (2008). Selecting a development approach. Webarticle. United States Department of Health and Human Services (HHS). Re-validated: March 27, 2008. Retrieved 27 Oct 2008.</ref>  Most modern development processes can be vaguely described as [[Agile software development|agile]]. Other methodologies include [[Waterfall model|waterfall]], [[Software prototyping|prototyping]], [[Iterative and incremental development|iterative and incremental development]], spiral development, [[Rapid application development|rapid application development]], and [[Extreme programming|extreme programming]].}}

{{term|[[Software engineering|software engineering]]}}
{{defn|Is the systematic application of [[Engineering:Engineering|engineering]] approaches to the [[Software development|development]] of [[Software|software]].<ref name="BoDu04">{{harvnb |Abran |Moore |Bourque| Dupuis |2004 |pp=1–1}}</ref><ref name="ACM 2020">{{cite web |last=ACM |year=2007 |url=http://computingcareers.acm.org/?page_id=12 |title=Computing Degrees & Careers |publisher=ACM |access-date=2010-11-23 |archive-date=2011-06-17 |archive-url=https://web.archive.org/web/20110617053818/http://computingcareers.acm.org/?page_id=12 |url-status=dead }}</ref><ref name="Laplante 2007">{{cite book |last=Laplante |first=Phillip |title=What Every Engineer Should Know about Software Engineering |publisher=CRC |location=Boca Raton |year=2007 |isbn=978-0-8493-7228-5 |url=https://books.google.com/books?id=pFHYk0KWAEgC&q=What%20Every%20Engineer%20Should%20Know%20about%20Software%20Engineering.&pg=PA1 |access-date=2011-01-21 }}</ref> Software engineering is a [[Computing|computing]] discipline.<ref>{{Cite web|url=http://www.acm.org/education/curric_vols/CC2005-March06Final.pdf|archive-url=https://web.archive.org/web/20141021153204/http://www.acm.org/education/curric_vols/CC2005-March06Final.pdf|archive-date=2014-10-21|title=The Joint Task Force for Computing Curricula 2005|date=2014-10-21|url-status=live|access-date=2020-04-16}}</ref>}}

{{term|[[Software maintenance|software maintenance]]}}
{{defn|In [[Software engineering|software engineering]] is the modification of a software product after delivery to correct faults, to improve performance or other attributes.<ref name="iso14764">{{cite web|url=http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=39064 |title=ISO/IEC 14764:2006 Software Engineering — Software Life Cycle Processes — Maintenance |publisher=Iso.org |date=2011-12-17 |access-date=2013-12-02}}</ref>}}

{{term|[[Software prototyping|software prototyping]]}}
{{defn|Is the activity of creating [[Engineering:Prototype|prototype]]s of software applications, i.e., incomplete versions of the [[Software|software program]] being developed. It is an activity that can occur in [[Software development process|software development]] and is comparable to prototyping as known from other fields, such as [[Engineering:Mechanical engineering|mechanical engineering]] or manufacturing.  A prototype typically simulates only a few aspects of, and may be completely different from, the final product. }}

{{term|[[Software requirements specification|software requirements specification]]}}
{{defn|(SRS), is a description of a [[Software system|software system]] to be  [[Software development|developed]]. The software requirements specification lays out [[Functional requirement|functional]] and non-functional requirements, and it may include a set of [[Use case|use case]]s that describe user interactions that the software must provide to the user for perfect interaction.}}

{{term|[[Software testing|software testing]]}}
{{defn|Is an investigation conducted to provide stakeholders with information about the [[Software quality|quality]] of the [[Software|software]] product or service under test.<ref name="Kaner 1">{{cite conference | url = http://www.kaner.com/pdfs/ETatQAI.pdf | title = Exploratory Testing | last = Kaner | first = Cem |conference=Quality Assurance Institute Worldwide Annual Software Testing Conference | location = Orlando, FL | date = November 17, 2006 | access-date = November 22, 2014}}</ref> Software testing can also provide an objective, independent view of the software to allow the business to appreciate and understand the risks of software implementation. Test techniques include the process of executing a program or application with the intent of finding [[Software bug|software bug]]s (errors or other defects), and verifying that the software product is fit for use. }}

{{term|[[Sorting algorithm|sorting algorithm]]}}
{{defn|Is an [[Algorithm|algorithm]] that puts elements of a list in a certain [[Total order|order]]. The most frequently used orders are numerical order and [[Lexicographical order|lexicographical order]]. Efficient [[Sorting|sorting]] is important for optimizing the [[Algorithmic efficiency|efficiency]] of other algorithms (such as [[Search algorithm|search]] and [[Merge algorithm|merge]] algorithms) that require input data to be in sorted lists. Sorting is also often useful for [[Canonicalization|canonicalizing]] data and for producing human-readable output. More formally, the output of any sorting algorithm must satisfy two conditions:

# The output is in nondecreasing order (each element is no smaller than the previous element according to the desired [[Total order|total order]]);<!-- confusing; this appears to mean that the output must be in ascending order, which isn't a necessary condition -->
# The output is a [[Permutation|permutation]] (a reordering, yet retaining all of the original elements) of the input.

Further, the input data is often stored in an [[Array data type|array]], which allows [[Random access|random access]], rather than a list, which only allows [[Sequential access|sequential access]]; though many algorithms can be applied to either type of data after suitable modification.
}}

{{term|[[Source code|source code]]}}
{{defn|In [[Computing|computing]], source code is any collection of code, with or without [[Comment (computer programming)|comments]], written using<ref>"Programming in C: A Tutorial" (PDF). Archived from the original(PDF) on 23 February 2015.</ref> a ''human-readable'' [[Programming language|programming language]], usually as [[Plain text|plain text]]. The source code of a program is specially designed to facilitate the work of computer [[Programmer|programmer]]s, who specify the actions to be performed by a computer mostly by writing source code. The source code is often transformed by an [[Assembler (computing)|assembler]] or [[Compiler|compiler]] into [[Binary number|binary]] [[Machine code|machine code]] that can be executed by the computer. The machine code might then be stored for [[Execution (computing)|execution]] at a later time. Alternatively, source code may be [[Interpreter (computing)|interpreted]] and thus immediately executed.}}

{{term|[[Spiral model|spiral model]]}}
{{defn|Is a risk-driven [[Software development process|software development process]] model. Based on the unique risk patterns of a given project, the spiral model guides a team to adopt elements of one or more process models, such as [[Iterative and incremental development|incremental]], [[Waterfall model|waterfall]], or [[Software prototyping#Evolutionary prototyping|evolutionary prototyping]].}}

{{term|[[Stack (abstract data type)|stack]]}}
{{defn|Is an [[Abstract data type|abstract data type]] that serves as a [[Collection (abstract data type)|collection]] of elements, with two main principal operations:
* {{visible anchor|push}}, which adds an element to the collection, and 
* {{visible anchor|pop}}, which removes the most recently added element that was not yet removed.
The order in which elements come off a stack gives rise to its alternative name, LIFO (last in, first out). Additionally, a [[Peek (data type operation)|peek]] operation may give access to the top without modifying the stack.<ref>By contrast, a simple QUEUE operates FIFO ([[FIFO (computing and electronics)|first in, first out]]).</ref> The name "stack" for this type of structure comes from the analogy to a set of physical items stacked on top of each other. This structure makes it easy to take an item off the top of the stack, while getting to an item deeper in the stack may require taking off multiple other items first.<ref name="clrs_pages_232-233">{{Introduction to Algorithms|3|pages=232–233}}</ref>}}

{{term|[[State (computer science)|state]]}}
{{defn|In [[Engineering:Information technology|information technology]] and computer science, a system is described as stateful if it is designed to remember preceding events or user interactions;<ref>{{cite web |url=http://whatis.techtarget.com/definition/stateless |title=What is stateless? - Definition from WhatIs.com |website=techtarget.com}}</ref> the remembered information is called the state of the system.}}

{{term|[[Statement (computer science)|statement]]}}
{{defn|In [[Computer programming|computer programming]], a statement is a [[Syntax (programming languages)|syntactic]] unit of an [[Imperative programming|imperative programming language]] that expresses some action to be carried out.<ref>{{cite web | url = http://www.webopedia.com/TERM/S/statement.html | title = statement | date = September 1996 | publisher = webopedia | access-date = 2015-03-03}}</ref> A [[Computer program|program]] written in such a language is formed by a sequence of one or more statements. A statement may have internal components (e.g., [[Expression (computer science)|expressions]]).}}

{{term|[[Computer data storage|storage]]}}
{{defn|Computer data storage is a technology consisting of [[Computer|computer]] components and [[Engineering:Data storage device|recording media]] that are used to retain digital [[Data (computing)|data]]. It is a core function and fundamental component of computers.<ref name="Patterson" />{{rp|15–16}}}}

{{term|[[Stream (computing)|stream]]}}
{{defn|Is a [[Sequence|sequence]] of [[Data element|data element]]s made available over time. A stream can be thought of as items on a [[Engineering:Conveyor belt|conveyor belt]] being processed one at a time rather than in large batches.}}

{{term|[[String (computer science)|string]]}}
{{defn|In [[Computer programming|computer programming]], a string is traditionally a [[Sequence|sequence]] of [[Character (computing)|characters]], either as a [[Literal (computer programming)|literal constant]] or as some kind of variable. The latter may allow its elements to be mutated and the length changed, or it may be fixed (after creation). A string is generally considered as a [[Data type|data type]] and is often implemented as an [[Array data structure|array data structure]] of [[Byte|byte]]s (or [[Word (computer architecture)|word]]s) that stores a sequence of elements, typically characters, using some [[Character encoding|character encoding]]. ''String'' may also denote more general [[Array data type|arrays]] or other sequence (or [[List (abstract data type)|list]]) data types and structures.}}

{{term|[[Structured storage|structured storage]]}}
{{defn|A NoSQL (originally referring to "non-[[SQL]]" or "non-relational")<ref>http://nosql-database.org/ "NoSQL DEFINITION: Next Generation Databases mostly addressing some of the points : being non-relational, distributed, open-source and horizontally scalable".</ref> [[Database|database]] provides a mechanism for [[Computer data storage|storage]] and [[Software:Data retrieval|retrieval]] of data that is modeled in means other than the tabular relations used in [[Relational database|relational database]]s. Such databases have existed since the late 1960s, but the name "NoSQL" was only coined in the early 21st century,<ref>Leavitt, Neal (2010). "Will NoSQL Databases Live Up to Their Promise?" (PDF). IEEE Computer. 43 (2): 12–14. doi:10.1109/MC.2010.58. S2CID 26876882.</ref> triggered by the needs of [[Social:Web 2.0|Web 2.0]] companies.<ref>{{cite conference |title=History Repeats Itself: Sensible and NonsenSQL Aspects of the NoSQL Hoopla |first=C. |last=Mohan |conference=Proc. 16th Int'l Conf. on Extending Database Technology |year=2013 |url=http://openproceedings.eu/2013/conf/edbt/Mohan13.pdf}}</ref><ref>{{cite web |url=https://www.wired.com/2012/01/amazon-dynamodb/ |title=Amazon Goes Back to the Future With 'NoSQL' Database |publisher=WIRED |date=2012-01-19 |access-date=2017-03-06}}</ref> NoSQL databases are increasingly used in [[Big data|big data]] and real-time web applications.<ref>{{cite web |url= http://db-engines.com/en/blog_post/23 |title= RDBMS dominate the database market, but NoSQL systems are catching up |publisher= DB-Engines.com |date= 21 Nov 2013 |access-date= 24 Nov 2013 }}</ref>  NoSQL systems are also sometimes called "Not only SQL" to emphasize that they may support [[SQL]]-like query languages or sit alongside SQL databases in [[Polyglot persistence|polyglot-persistent]] architectures.<ref>{{cite web |url=http://searchdatamanagement.techtarget.com/definition/NoSQL-Not-Only-SQL |title=NoSQL (Not Only SQL) |quote=NoSQL database, also called Not Only SQL}}</ref><ref>{{cite web | url = http://martinfowler.com/bliki/NosqlDefinition.html | title = NosqlDefinition | first = Martin | last = Fowler |  quote = many advocates of NoSQL say that it does not mean a "no" to SQL, rather it means Not Only SQL }}</ref>}}

{{term|[[Subroutine|subroutine]]}}
{{defn|In [[Computer programming|computer programming]], a subroutine is a sequence of program instructions that performs a specific task, packaged as a unit. This unit can then be used in programs wherever that particular [[Task (computing)|task]] should be performed.  {{anchor|SUBROUTINE_DEFINITION}}Subroutines may be defined within programs, or separately in libraries that can be used by many programs.  In different programming languages, a subroutine may be called a routine, subprogram, function, method, or procedure. Technically, these terms all have different definitions. The generic, umbrella term  callable unit is sometimes used.<ref name="U.S. Election Assistance Commission 2007">{{cite web
 |author      = U.S. Election Assistance Commission
 |title       = Definitions of Words with Special Meanings
 |work        = Voluntary Voting System Guidelines
 |year        = 2007
 |url         = http://www.eac.gov/vvsg/glossary.aspx
 |access-date  = 2013-01-14
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20121208084203/http://www.eac.gov/vvsg/glossary.aspx
 |archive-date = 2012-12-08
}}</ref>}}

{{term|symbolic computation}}
{{defn|In [[Mathematics|mathematics]] and [[Computer science|computer science]],<ref>{{Cite web |title=ACM Association in computer algebra |url=https://www.sigsam.org/cca/}}</ref> computer algebra, also called symbolic computation or algebraic computation, is a scientific area that refers to the study and development of [[Algorithm|algorithm]]s and [[Software|software]] for manipulating [[Expression (mathematics)|mathematical expressions]] and other [[Philosophy:Mathematical object|mathematical object]]s. Although computer algebra could be considered a subfield of scientific computing, they are generally considered as distinct fields because scientific computing is usually based on numerical computation with approximate floating point numbers, while symbolic computation emphasizes ''exact'' computation with expressions containing [[Variable (mathematics)|variable]]s that have no given value and are manipulated as symbols.}}

{{term|[[Syntax (programming languages)|syntax]]}}
{{defn|The syntax of a [[Computer language|computer language]] is the set of rules that defines the combinations of symbols that are considered to be correctly structured [[Statement (computer science)|statement]]s or [[Expression (computer science)|expression]]s in that language. This applies both to [[Programming language|programming language]]s, where the document represents [[Source code|source code]], and to [[Markup language|markup language]]s, where the document represents data.}}

{{term|[[Syntax error|syntax error]]}}
{{defn|Is an error in the [[Syntax (programming languages)|syntax]] of a sequence of characters or tokens that is intended to be written in [[Compiler|compile-time]]. A program will not compile until all syntax errors are corrected. For [[Interpreted language|interpreted language]]s, however, a syntax error may be detected during [[Run time (program lifecycle phase)|program execution]], and an interpreter's error messages might not differentiate syntax errors from errors of other kinds. There is some disagreement as to just what errors are "syntax errors". For example, some would say that the use of an uninitialized variable's value in Java code is a syntax error, but many others would disagree<ref>[https://stackoverflow.com/questions/8803718/issue-of-syntax-or-semantics/8803765#8803765 Issue of syntax or semantics?]</ref><ref>[https://www.dummies.com/programming/java/semantic-errors-in-java/ John Paul Mueller,Semantic Errors in Java]</ref> and would classify this as a [[Programming language#Static semantics|(static) semantic]] error.}}

{{term|[[System console|system console]]}}
{{defn|The system console, computer console, root console, [[Computer operator|operator]]'s console, or simply console is the text entry and display device for system administration messages, particularly those from the [[BIOS]] or [[Boot loader|boot loader]], the [[Software:Kernel (operating system)|kernel]], from the [[Software:Init|init]] system and from the [[Software:Syslog|system logger]]. It is a physical device consisting of a keyboard and a screen, and traditionally is a text terminal, but may also be a [[Engineering:Graphical terminal|graphical terminal]]. System consoles are generalized to [[Computer terminal|computer terminal]]s, which are abstracted respectively by [[Virtual console|virtual console]]s and [[Terminal emulator|terminal emulator]]s. Today communication with system consoles is generally done abstractly, via the [[Standard streams|standard streams]] (stdin, stdout, and stderr), but there may be system-specific interfaces, for example those used by the system kernel.}}
{{glossaryend}}

==T==
{{glossary}}
{{term|[[Technical documentation|technical documentation]]}}
{{defn|In engineering, any type of [[Documentation|documentation]] that describes handling, functionality, and architecture of a technical product or a product under development or use.<ref>[http://www.transcom.de/transcom/en/technische-dokumentation.htm What is "technical documentation"?] at Transcom.de. Accessed February 25, 2013.</ref><ref>[http://www.tetras.sk/en/stranka/what-is-technical-documentation What is Technical Documentation?] {{Webarchive|url=https://archive.today/20130418132550/http://www.tetras.sk/en/stranka/what-is-technical-documentation |date=2013-04-18 }} at Tetras Translations. Accessed February 25, 2013.</ref><ref>[http://www.igcseict.info/theory/8/docs/index.html Documenting the New System] at IGCSE ICT. Accessed February 25, 2013.</ref> The intended recipient for product technical documentation is both the (proficient) {{gli|end user}} as well as the administrator/service or maintenance technician. In contrast to a mere "cookbook" [[User guide|manual]], technical documentation aims at providing enough information for a user to understand inner and outer dependencies of the product at hand.}}

{{term|[[Third-generation programming language|third-generation programming language]]}}
{{defn|A third-generation programming language (3GL) is a [[High-level programming language|high-level]] computer [[Programming language|programming language]] that tends to be more machine-independent and programmer-friendly than the [[Machine code|machine code]] of the [[First-generation programming language|first-generation]] and [[Assembly language|assembly language]]s of the [[Second-generation programming language|second-generation]], while having a less specific focus to the [[Fourth-generation programming language|fourth]] and [[Fifth-generation programming language|fifth]] generations.<ref name="Computer Hope">[http://www.computerhope.com/jargon/num/1gl.htm "Computer Hope, Generation languages"]</ref> Examples of common and historical third-generation programming languages are [[ALGOL]], [[BASIC]], [[C (programming language)|C]], [[COBOL]], [[Fortran]], [[Java (programming language)|Java]], and [[Pascal (programming language)|Pascal]].}}

{{term|[[Top-down and bottom-up design|top-down and bottom-up design]]}}
{{defn|}}

{{term|[[Tree (data structure)|tree]]}}
{{defn|A widely used {{gli|abstract data type}} (ADT) that simulates a hierarchical [[Tree structure|tree structure]], with a root value and subtrees of children with a {{gli|parent node}}, represented as a set of linked {{gli|node|nodes}}.}}

{{term|[[Type theory|type theory]]}}
{{defn|In mathematics, logic, and computer science, a type theory is any of a class of [[Formal system|formal system]]s, some of which can serve as alternatives to [[Set theory|set theory]] as a [[Philosophy:Foundations of mathematics|foundation for all mathematics]]. In type theory, every "term" has a "type" and operations are restricted to terms of a certain type.}}
{{glossaryend}}

==U==
{{glossary}}
{{term|[[Upload|upload]]}}
{{defn|In [[Computer network|computer network]]s, to send [[Data (computing)|data]] to a remote system such as a [[Server (computing)|server]] or another client so that the remote system can store a copy.<ref>{{Cite web|url=https://techterms.com/definition/upload|title=Upload Definition|website=techterms.com|language=en|access-date=2017-03-30}}</ref> Contrast ''{{gli|download}}''.}}

{{term|[[URL|Uniform Resource Locator]] (URL)}}
{{ghat|Colloquially '''web address'''.{{sfnp|W3C|2009}}}}
{{defn|A reference to a [[Web resource|web resource]] that specifies its location on a [[Computer network|computer network]] and a mechanism for retrieving it. A URL is a specific type of [[Uniform Resource Identifier]] (URI),<ref>{{Cite web|url=https://zzz.buzz/2017/09/19/forward-and-backslashes-in-urls/|title=Forward and Backslashes in URLs|website=zzz.buzz|language=en|access-date=2018-09-19}}</ref>{{sfnp|RFC 3986|2005}} although many people use the two terms interchangeably.{{sfnp|Joint W3C/IETF URI Planning Interest Group|2002}}{{efn|A URL implies the means to access an indicated resource and is denoted by a protocol or an access mechanism, which is not true of every URI.{{sfnp|RFC 2396|1998}}{{sfnp|Joint W3C/IETF URI Planning Interest Group|2002}}  Thus <code><nowiki>http:</nowiki>//www.example.com</code> is a URL, while <code>www.example.com</code> is not.<ref>{{Cite web|url=https://danielmiessler.com/study/url-uri/#gs.Hs64zOs|title=The Difference Between URLs and URIs|last=Miessler|first=Daniel}}</ref>}} URLs occur most commonly to reference web pages (http), but are also used for file transfer ([[File Transfer Protocol|ftp]]), email ([[Mailto|mailto]]), database access ([[Software:Java Database Connectivity|JDBC]]), and many other applications.}}

{{term|[[User (computing)|user]]}}
{{defn|Is a person who utilizes a [[Computer|computer]] or [[Computer network|network]] [[Service (systems architecture)|service]]. Users of computer systems and software products generally lack the technical expertise required to fully understand how they work.<ref name=":0">[[Jargon File]] entry for {{cite web |url=http://catb.org/jargon/html/U/user.html |title=User |access-date=November 7, 2010}}</ref> [[Power user]]s use advanced features of programs, though they are not necessarily capable of [[Computer programming|computer programming]] and system administration.}}

{{term|[[User agent|user agent]]}}
{{defn|Software (a {{gli|software agent}}) that acts on behalf of a {{gli|user}}, such as a [[Software:Web browser|web browser]] that "retrieves, renders and facilitates end user interaction with Web content".<ref>{{cite web|url=https://www.w3.org/WAI/UA/work/wiki/Definition_of_User_Agent |title=W3C Definition of User Agent |publisher=www.w3.org |date=16 June 2011 |access-date=2018-10-20}}</ref> An email reader is a mail user agent.}}

{{term|[[User interface|user interface]] (UI)}}{{anchor|user interface}}
{{defn|The space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine from the human end, whilst the machine simultaneously feeds back information that aids the operators' [[Decision-making|decision-making]] process. Examples of this broad concept of user interfaces include the interactive aspects of computer [[Operating system|operating system]]s, hand tools, heavy machinery operator controls, and [[Chemistry:Unit operation|process]] controls. The design considerations applicable when creating user interfaces are related to or involve such disciplines as ergonomics and [[Social:Psychology|psychology]].}}

{{term|[[User interface design|user interface design]]}}
{{ghat|Also '''user interface engineering'''.}}
{{defn|The design of {{gli|user interface|user interfaces}} for machines and {{gli|software}}, such as computers, home appliances, mobile devices, and other electronic devices, with the focus on maximizing [[Usability|usability]] and the [[User experience|user experience]]. The goal of user interface design is to make the user's interaction as simple and efficient as possible, in terms of accomplishing user goals ([[User-centered design|user-centered design]]).}}
{{glossaryend}}

==V==
{{glossary}}
{{term|[[Variable (computer science)|variable]]}}
{{defn|In {{gli|computer programming}}, a variable, or scalar, is a storage location (identified by a [[Memory address|memory address]]) paired with an associated symbolic name (an ''{{gli|identifier}}''), which contains some known or unknown quantity of information referred to as a ''{{gli|value}}''. The variable name is the usual way to {{gli|reference}} the stored value, in addition to referring to the variable itself, depending on the context. This separation of name and content allows the name to be used independently of the exact information it represents. The identifier in computer {{gli|source code}} can be [[Name binding|bound]] to a value during [[Run time (program lifecycle phase)|run time]], and the value of the variable may therefore change during the course of {{gli|execution|program execution}}.<ref>{{citation | title=Compilers: Principles, Techniques, and Tools | pages=26–28| title-link=Compilers: Principles, Techniques, and Tools| year=1986| bibcode=1986cptt.book.....A| last1=Aho| first1=Alfred V.| last2=Sethi| first2=Ravi| last3=Ullman| first3=Jeffrey D.}}</ref><ref>{{cite book |last=Knuth |first=Donald |date=1997 |title=The Art of Computer Programming |volume=1 |edition=3rd |location=Reading, Massachusetts |publisher=Addison-Wesley |pages=3–4 |isbn=0-201-89683-4 }}</ref>}}

{{term|[[Virtual machine|virtual machine]] (VM)}}{{anchor|virtual machine}}
{{defn|An {{gli|emulator|emulation}} of a computer system. Virtual machines are based on {{gli|computer architecture|computer architectures}} and attempt to provide the same functionality as a physical computer. Their implementations may involve specialized hardware, software, or a combination of both.}}

{{term|[[Software:V-Model (software development)|V-Model]]}}
{{defn|A [[Software development process|software development process]] that may be considered an extension of the {{gli|waterfall model}}, and is an example of the more [[V-model|general V-model]]. Instead of moving down in a linear way, the process steps are bent upwards after the {{gli|source code|coding}} phase, to form the typical V shape. The V-Model demonstrates the relationships between each phase of the development life cycle and its associated phase of [[Software testing|testing]]. The horizontal and vertical axes represent time or project completeness (left-to-right) and level of abstraction (coarsest-grain abstraction uppermost), respectively.<ref>[[Biography:Kevin Forsberg|Kevin Forsberg]] and [[Biography:Harold Mooz|Harold Mooz]], "The Relationship of System Engineering to the Project Cycle", in Proceedings of the First Annual Symposium of National Council on System Engineering, October 1991: 57–65.</ref>}}
{{glossaryend}}

==W==
{{glossary}}
{{term|[[Waterfall model|waterfall model]]}}
{{defn|A breakdown of project activities into linear [[Sequence|sequential]] phases, where each phase depends on the deliverables of the previous one and corresponds to a specialisation of tasks.  The approach is typical for certain areas of engineering design. In [[Software development process|software development]], it tends to be among the less iterative and flexible approaches, as progress flows in largely one direction ("downwards" like a [[Earth:Waterfall|waterfall]]) through the phases of conception, initiation, [[Philosophy:Analysis|analysis]], [[Software design|design]], [[Software construction|construction]], [[Software testing|testing]], [[Implementation|deployment]] and [[Software maintenance|maintenance]].}}

{{term|[[WAV|Waveform Audio File Format]]}}
{{ghat|Also '''WAVE''' or '''WAV''' due to its [[Filename extension|filename extension]].}}
{{defn|An [[Audio file format|audio file format]] standard, developed by [[Company:Microsoft|Microsoft]] and IBM, for storing an audio bitstream on [[Engineering:Personal computer|PCs]]. It is an application of the [[Resource Interchange File Format]] (RIFF) [[Bitstream format|bitstream format]] method for storing data in "chunks", and thus is also close to the [[8SVX|8SVX]] and the [[Audio Interchange File Format|AIFF]] format used on [[Engineering:Amiga|Amiga]] and [[Software:Apple Macintosh|Macintosh]] computers, respectively. It is the main format used on [[Software:Microsoft Windows|Microsoft Windows]] systems for raw and typically uncompressed audio. The usual bitstream encoding is the linear pulse-code modulation (LPCM) format.}}

{{term|[[Web crawler|web crawler]]}}
{{ghat|Also '''spider''', '''spiderbot''', or simply '''crawler'''.}}
{{defn|An {{gli|Internet bot}} that systematically browses the [[World Wide Web]], typically for the purpose of [[Web indexing]] (''web spidering'').}}

{{term|[[Wi-Fi]]}}
{{defn|A family of wireless networking technologies, based on the [[IEEE 802.11]] family of standards, which are commonly used for [[Wireless LAN|local area network]]ing of devices and [[Internet]] access. ''Wi{{nbh}}Fi'' is a trademark of the non-profit [[Organization:Wi-Fi Alliance|Wi-Fi Alliance]], which restricts the use of the term ''Wi-Fi Certified'' to products that successfully complete interoperability certification testing.<ref>{{cite web|url=http://www.webopedia.com/TERM/W/Wi_Fi.html|title=What is Wi-Fi (IEEE 802.11x)? A Webopedia Definition|last=Beal|first=Vangie|website=Webopedia|date=2 May 2001|archive-url=https://web.archive.org/web/20120308123721/http://www.webopedia.com/term/w/wi_fi.html|archive-date=2012-03-08|url-status=live}}</ref><ref>{{Cite web|url=https://www.theguardian.com/technology/blog/2007/may/21/thedangersof|title=The dangers of Wi-Fi radiation (updated)|first=Jack|last=Schofield|date=21 May 2007|via=www.theguardian.com}}</ref><ref>{{Cite web|url=https://www.wi-fi.org/certification|title=Certification &#124; Wi-Fi Alliance|website=www.wi-fi.org}}</ref>}}
{{glossaryend}}

==X==
{{glossary}}
{{term|[[XHTML]]}}
{{ghat|Abbreviaton of '''eXtensible HyperText Markup Language'''.}}
{{defn|Part of the family of [[XML]] [[Markup language|markup language]]s. It mirrors or extends versions of the widely used HyperText Markup Language (HTML), the language in which [[Web page|web page]]s are formulated.}}
{{glossaryend}}


==See also==
*[[Outline of computer science]]

==References==
{{reflist}}

===Works cited===
{{refbegin|2}}
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* {{cite book |first1=Alain |last1=Abran |first2=James W. |last2=Moore |first3=Pierre |last3=Bourque |first4=Robert |last4=Dupuis |first5=Leonard L. |last5=Tripp |title=Guide to the Software Engineering Body of Knowledge |year=2004 |publisher=IEEE |isbn=978-0-7695-2330-9}}
* {{Citation |first1=Howard |last1=Anton |year=1987 |isbn=0-471-84819-0 |title=Elementary Linear Algebra |edition=5th |publisher=Wiley |location=New York}}
<!-- B -->
* {{Citation |first1=Raymond A. |last1=Beauregard |first2=John B. |last2=Fraleigh |year=1973 |isbn=0-395-14017-X |title=A First Course In Linear Algebra: with Optional Introduction to Groups, Rings, and Fields |publisher=Houghton Mifflin Co. |location=Boston |url-access=registration |url=https://archive.org/details/firstcourseinlin0000beau}}
* {{cite IETF |rfc=2396 |title=Uniform Resource Identifiers (URI): Generic Syntax |author-first1=Tim |author-last1=Berners-Lee |author-first2=Roy T. |author-last2=Fielding |author-link2=Roy T. Fielding |author-first3=Larry |author-last3=Masinter |author-link3=Larry Masinter |date=August 1998 |access-date=31 August 2015 |ref={{SfnRef|RFC 2396|1998}}}}
* {{cite IETF |rfc=3986 |title=Uniform Resource Identifiers (URI): Generic Syntax |author-first1=Tim |author-last1=Berners-Lee |author-first2=Roy T. |author-last2=Fielding |author-link2=Roy T. Fielding |author-first3=Larry |author-last3=Masinter |author-link3=Larry Masinter |date=January 2005 |access-date=31 August 2015 |ref={{SfnRef|RFC 3986|2005}}}}
* {{cite book |last1=Bruce |first1=Kim B. |title=Foundations of Object-oriented Languages: Types and Semantics |date=2002 |publisher=MIT Press |isbn=978-0-262-02523-2 |url=https://books.google.com/books?id=9NGWq3K1RwUC&pg=PA18 |language=en}}
* {{cite book |last1=Butterfield |first1=Andrew |last2=Ngondi |first2=Gerard E. |title=A dictionary of computer science |date=2016 |publisher=[[Organization:Oxford University Press|Oxford University Press]] |location=Oxford, UK |isbn=978-0-19-968897-5 |edition=7th}}
<!-- C -->
* {{cite web |url=http://www.w3.org/html/wg/href/draft#url |title=Web addresses in HTML 5 |editor-first1=Daniel "Dan" |editor-last1=Connolly |editor-first2=C. Michael |editor-last2=Sperberg-McQueen |editor-link2=C. Michael Sperberg-McQueen |date=21 May 2009 |publisher=[[Organization:World Wide Web Consortium|World Wide Web Consortium]] |access-date=13 September 2015 |ref={{SfnRef|W3C|2009}} |archive-date=2015-07-10 |archive-url=https://web.archive.org/web/20150710151425/http://www.w3.org/html/wg/href/draft#url |url-status=live}}
<!-- G -->
* {{cite book |last1=Gamma |last2=Helm |last3=Johnson |last4=Vlissides |year=1995 |title=Design Patterns: Elements of Reusable Object-Oriented Software |url=https://archive.org/details/designpatternsel00gamm |url-access=registration |publisher=Addison Wesley |isbn=9780201633610}}
* {{cite book |last1=Gosling |first1=James |last2=Joy |first2=Bill |last3=Steele |first3=Guy |last4=Bracha |first4=Gilad |last5=Buckley |first5=Alex |title=The Java® Language Specification |date=2014 |edition=Java SE 8 |url=https://docs.oracle.com/javase/specs/jls/se8/jls8.pd}}
<!-- H -->
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* {{cite book |last=Knuth |first=Donald |year=1998 |title=Sorting and searching |series=[[The Art of Computer Programming]] |volume=3 |edition=2nd |location=Reading, MA |publisher=Addison-Wesley Professional |isbn=978-0-201-89685-5}}
<!-- L -->
* {{cite arXiv |last1=Legg |first1=Shane |last2=Hutter |first2=Marcus |date=15 June 2007 |title=A Collection of Definitions of Intelligence |class=cs.AI |eprint=0706.3639}}
<!-- M -->
* {{cite IETF |rfc=3305 |title=Report from the Joint W3C/IETF URI Planning Interest Group: Uniform Resource Identifiers (URIs), URLs, and Uniform Resource Names (URNs): Clarifications and Recommendations |editor-first1=Michael |editor-last1=Mealling |editor-first2=Ray |editor-last2=Denenberg |date=August 2002 |access-date=13 September 2015 |ref={{SfnRef|Joint W3C/IETF URI Planning Interest Group|2002}}}}
* {{Cite book |last=Mitchell |first=Melanie |title=An Introduction to Genetic Algorithms |year=1996 |publisher=MIT Press |location=Cambridge, MA |isbn=9780585030944}}
<!-- N -->
* {{cite book |last=Nilsson |first=Nils |year=1998 |title=Artificial Intelligence: A New Synthesis |url=https://archive.org/details/artificialintell0000nils |url-access=registration |publisher=Morgan Kaufmann |isbn=978-1-55860-467-4 |access-date=18 November 2019 |archive-date=26 July 2020 |archive-url=https://web.archive.org/web/20200726131654/https://archive.org/details/artificialintell0000nils |url-status=live}}
<!-- P -->
* {{cite book |first1=David |last1=Poole |first2=Alan |last2=Mackworth |first3=Randy |last3=Goebel |year=1998 |title=Computational Intelligence: A Logical Approach |publisher=Oxford University Press |location=New York |isbn=978-0-19-510270-3 |url=https://archive.org/details/computationalint00pool |access-date=22 August 2020 |archive-date=26 July 2020 |archive-url=https://web.archive.org/web/20200726131436/https://archive.org/details/computationalint00pool |url-status=live}}
<!-- R -->
* {{Russell Norvig 2003}}
* {{Cite book |first1=Stuart J. |last1=Russell |first2=Peter |last2=Norvig |title=[[Artificial Intelligence: A Modern Approach| A Modern Approach]] <!-- |url=http://aima.cs.berkeley.edu/ --> |year=2009 |edition=3rd |publisher=Prentice Hall |location=Upper Saddle River, New Jersey |isbn=978-0-13-604259-4 |}}.
<!-- T -->
{{refend}}

==Notes==
{{reflist|group=lower-alpha}}

{{Computer science}}
{{Software engineering}}
{{Glossaries of science and engineering}}

[[Category:Computer science| ]]
[[Category:Glossaries of computers|science]]
[[Category:Computers]]

{{Sourceattribution|Glossary of computer science}}