View source for Help:Overview of referencing styles

{{Wikipedia how to}}
{{notice|This help page is an overview and gives concise examples of several systems. Please refer to the linked main articles for details. For a more general introduction see [[Help:Introduction to referencing]] or [[Help:Referencing for beginners with citation templates]].}}

Wikipedia uses various ''referencing systems'' to [[Wikipedia:Citing sources|cite sources]] that support assertions in the article and to add explanatory and supplementary material. This page compares two systems that are currently used ([[#Footnotes|Footnotes]] and [[#Shortened footnotes|Shortened footnotes]]) and two older systems that are deprecated and no longer used for new articles ([[#Footnote3|Footnote3]] and [[#Parenthetical referencing|Parenthetical referencing]]).

==Systems currently used==

===Footnotes===
{{main|Help:Footnotes}}
Wikipedia footnotes are a specific method of creating in-text cites and reference lists using the {{Cite.php}} software extension. This should not be confused with the concept of footnotes in general.

The in-text cite is placed in the content, usually after punctuation, and is created by enclosing the citation or note within {{tag|ref}} tags. Each in-text cite is formatted as a superscripted alphanumeric character called the cite label and is enclosed by brackets; example:{{dummy ref}}. The cite label has an HTML link to the full citation in the reference list. In-text cites are automatically ordered by the cite label starting from the first use on a page. The cite labels default to decimal but can be styled as alphabetic, Roman or Greek. The in-text cite may be defined with a name so they can be reused within the content and may be separated into groups for use as explanatory notes, table legends and the like.

The reference list shows the full citations with a cite label that matches the in-text cite. The cite label is a caret {{dummy backlink}} with a backlink to the in-text cite. When a named in-text cite is invoked multiple times, multiple alphabetic back links are created after the cite label in the reference list.

The reference list is created by use of the {{tag|references|s}} tag or the {{tl|reflist}} template. Example:

{{markup
|<nowiki>This is an in-text cite.<ref>citation</ref>

==References==
<references />
</nowiki>
|This is an in-text cite.<ref>citation</ref>

{{fake heading|sub=3|References}}
<references />
}}

===Shortened footnotes===
{{main|Help:Shortened footnotes}}

In this short example, note that an in-text cite such as {{dummy ref}} links to the shortened citation in the Notes list, which in turn links to the long citation in the References list:

{{markup
|<nowiki>The brontosaurus is thin at one end.{{sfn|Elk|1972|p=5}} Then it becomes much thicker in the middle.{{sfn|Elk|1972|p=6}}
The Norwegian Blue Parrot will not move if its feet are nailed to the perch.{{sfn|Praline|1969|p=12}} Its metabolic processes are a matter of interest only to historians.{{sfn|Praline|1969|p=16}}

==Notes==
{{reflist}}

==References==
{{refbegin}}
*{{cite book |last=Elk |first=Anne |title=[[Anne Elk's Theory on Brontosauruses]] |date=November 16, 1972 }}
*{{cite book |last=Praline |first=Eric |title=[[Dead Parrot sketch]] |date=December 7, 1969 }}
{{refend}}</nowiki>
|The brontosaurus is thin at one end.{{sfn|Elk|1972|p=5}} Then it becomes much thicker in the middle.{{sfn|Elk|1972|p=6}}
The Norwegian Blue Parrot will not move if its feet are nailed to the perch.{{sfn|Praline|1969|p=12}} Its metabolic processes are a matter of interest only to historians.{{sfn|Praline|1969|p=16}}
{{fake heading|sub=3|Notes}}
{{reflist|2}}
{{fake heading|sub=3|References}}
{{refbegin}}
*{{cite book |last=Elk |first=Anne |title=[[Anne Elk's Theory on Brontosauruses]] |date=November 16, 1972 }}
*{{cite book |last=Praline |first=Eric |title=[[Dead Parrot sketch]] |date=December 7, 1969 }}
{{refend}}
}}

==Older deprecated systems==

===Footnote3===
{{main|Wikipedia:Footnote3}}
Footnote3 is a [[deprecation|deprecated]] method of referencing. New articles should not be created with it. Although it appears similar to the Footnotes system, it uses the {{tl|ref}} and {{tl|note}} templates.

{{markup
|<nowiki>According to scientists, the Sun is pretty big.{{ref|1}}
The Moon, however, is not so big.{{ref|2}}

==Notes==
# {{note|1}} Miller, E: "The Sun.", page 23. Academic Press, 2005
# {{note|2}} Smith, R: "Size of the Moon", ''Scientific American'', 46(78):46</nowiki>
|According to scientists, the Sun is pretty big.{{ref|1}}
The Moon, however, is not so big.{{ref|2}}

{{fake heading|sub=3|Notes}}
# {{note|1}} Miller, E: "The Sun.", page 23. Academic Press, 2005
# {{note|2}} Smith, R: "Size of the Moon", ''Scientific American'', 46(78):46
}}

{| class="wikitable"
|+ Comparison of Footnote3 and Cite.php Footnote
! !! Footnote3 !! Cite.php
|-
| Use                  || Deprecated for standard footnotes{{r|footnote3}}              || Standard{{r|footnote}}
|-
| Number style         || User applied, free style: can use numbers, alpha, Greek, etc. || Automatic with several styles{{r|citelabel}}
|-
| Reference list order || Manual                                                        || Automatic
|-
| Nesting              || Can nest {{tag|ref}} and other templates                      || Nesting with limitations{{r|refnest}}
|-
| Reuse                || Yes, but creates duplicate HTML ids{{r|htmlid}}               || Yes, unique HTML ids{{r|citebacklinks}}
|-
| Error checking       || No{{r|referror}}                                              || Yes{{r|citeerror}}
|-
| Markup               || Fairly terse                                                  || Can be a bit long, especially when using groups
|-
| Preview testing      || Clicking on a {{tl|ref}} link while previewing an edit will cause the page to reload and changes to be lost || No issues
|}

===Parenthetical referencing===
{{main|Wikipedia:Parenthetical referencing}}
[[Parenthetical referencing]] is a [[citation]] system in which citations are added within sentences using [[brackets]] (parentheses). An example would be "Paris is the capital of France (Smith 2020, p.&nbsp;1)". Full citations are collected in footnotes or endnotes, or in alphabetical order by author's last name, under a "references", "bibliography", or "works cited" heading at the end of the text.

This style of citation was a type of referencing used on Wikipedia until September 2020, when a [[Special:PermanentLink/976895063#Deprecate parenthetical citations|community discussion]] reached a consensus to [[deprecation|deprecate]] this format of citation. While some existing articles may still use this form of citation, new articles should not be created with it.

==See also==
* [[Help:References and page numbers]]

==Notes==
{{reflist |refs=
<ref name=citebacklinks>A large number of reuses of a cite will result in a long sequence of backlinks that are unwieldy and useless; see {{phab|25455}}.</ref>
<ref name=citeerror>See [[Help: Cite errors]].</ref>
<ref name=citelabel>See [[Help:Shortened footnotes]]</ref>
<ref name=referror>It is possible to define a Note without a matching Ref or vice versa. Example: {{oldid|Governor of New York|349745548|Governor of New York}} invokes Ref but never defines the references.</ref>
<ref name=footnote>See [[Help:Footnotes]]</ref>
<ref name=footnote3>See [[Wikipedia:Footnote3]]</ref>
<ref name=htmlid>{{tl|Ref}} creates an HTML id for the backlink ; when using {{tl|Ref}} multiple times, the id is the same:
*Per the HTML spec, ids must be unique, thus reuse causes [[Help:Markup validation|validation errors]] in the articles where the template is transcluded.
*Backlinks from the reference list to the inline cite are ambiguous—  FireFox and Internet Explorer backlink only to the first inline cite, Opera backlinks to the last.
*Example: See the use of the dagger symbol in {{oldid|List of baryons|350423039|List of baryons}} and the [http://validator.w3.org/check?uri=http%3A%2F%2Fen.wikipedia.org%2Fw%2Findex.php%3Ftitle%3DList_of_baryons%26oldid%3D350423039&charset=%28detect+automatically%29&doctype=Inline&group=0 W3C validation]— the HTML id for the dagger is "ref_Undiscovered".</ref>
<ref name=refnest>See [[WP:REFNEST]]</ref>
}}

{{Wikipedia referencing}}