This help page is a how-to guide. It details processes or procedures of some aspect(s) of Wikipedia's norms and practices. It is not one of Wikipedia's policies or guidelines, and may reflect varying levels of consensus and vetting.

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 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 and Shortened footnotes) and two older systems that are deprecated and no longer used for new articles (Footnote3 and Parenthetical referencing).

Footnotes

Wikipedia footnotes are a specific method of creating in-text cites and reference lists using the Cite 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 <ref>...</ref> tags. Each in-text cite is formatted as a superscripted alphanumeric character called the cite label and is enclosed by brackets; example:^[1]. 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 ^{^} 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 <references /> tag or the ((reflist)) template. Example:

This is an in-text cite.<ref>citation</ref>

==References==
<references />

Shortened footnotes

In this short example, note that an in-text cite such as ^[1] links to the shortened citation in the Notes list, which in turn links to the long citation in the References list:

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))

Footnote3

Footnote3 is a deprecated method of referencing. New articles should not be created with it. Although it appears similar to the Footnotes system, it uses the ((ref)) and ((note)) templates.

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

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. 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 community discussion reached a consensus to deprecate this format of citation. While some existing articles may still use this form of citation, new articles should not be created with it.

• Help:References and page numbers