Wikipedia:Manual of Style/Footnotes: Difference between revisions

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This page documents an English Wikipedia style guideline.

Editors should generally follow it, though exceptions may apply. Substantive edits to this page should reflect consensus. When in doubt, discuss first on this guideline's talk page.

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A footnote is a note placed at the bottom of a page of a document to comment on a part of the main text, or to provide a reference for it, or both. The connection between the relevant text and its footnote is indicated by a number or symbol which appears both after the relevant text and before the footnote.

Footnotes are sometimes useful for relevant text that would distract from the main point if embedded in the main text, yet are helpful in explaining a point in greater detail. Footnotes are also often used to cite references that are relevant to a text. Wikipedia:Verifiability, a key content policy, says that any uncited information may be removed from an article - and if it is, the burden of proof is on the editor who wishes to re-add the information, to back it up with a citation.

Footnotes are one way to cite sources. Alternative methods are embedded citations and Harvard referencing (also commonly known as author-date or parenthetical referencing). For more information, see Wikipedia:Citing sources, the main style guide on citations.

You can add a footnote to an article by writing your note within <ref> ... </ref> tags, as explained below.

An older system using {{ref}} and {{note}} templates is still common. Converting this older system^[1] to the new <ref>...</ref> system can make the references in an article easier to maintain.

How to use

A very simplified explanation is given at Help:Footnotes

Place a <ref> ... </ref> where you want a footnote reference number to appear in an article—type the text of the note between the ref tags.
Place the <references /> tag in a "Notes" or "References" section near the end of the article—the list of notes will be generated here.

This page itself uses footnotes, such as the one at the end of this sentence.^[2] If you view the Wikicode of this page by clicking "Edit this page", you can see a working example of footnotes. For the purpose of adding references, the more recent cannot be mixed on a page with the old Footnotes3 format—you must pick one or the other. It is possible, however, to use the template system to e.g. separate content notes and references when that is deemed a good idea (this is often the case when content notes must be themselves cited, see, for example, Alcibiades).

Where to place ref tags

Place a ref tag at the end of the term, phrase, sentence, or paragraph to which the note refers.^[3]

When placed at the end of a clause or sentence the ref tag should be directly after the punctuation mark without an intervening space,^[3] in order to prevent the reference number wrapping to the next line.^[3] The same is true for successive ref tags.^[2]^[3] The exception is a dash^[3]—which should follow the ref tag. This is the format recommended by the Chicago Manual of Style.^[4]

Example:

According to scientists, the Sun is pretty big;<ref>Miller, E: "The Sun.", page 23. Academic Press, 2005.</ref> however, the moon is not so big.<ref>Smith, R: "Size of the Moon", ''Scientific American'', 46(78):46.</ref> == Notes == <references />

Citing a footnote more than once

To give a footnote a unique identifier, use <ref name="name"> ... </ref>. You can then refer to the same footnote again by using a ref tag with the same name. The name cannot be a number, or the extension will return an error. The ref name need not be placed within quotes unless it consists of more than one word (the wiki parser converts single word quoteless attribute values into validly quoted XHTML).

Though some printed texts use ibid, ditto, or similar shorthand for multiple references, Wiki is not paper. Please do not use "ibid" or other footnote shorthands. The available tools for multiple references are more powerful.

Only the first occurrence of text in a named ref will be used, although that occurrence may be located anywhere in the article. You can either copy the whole footnote, or you can use a terminated empty ref tag that looks like this: <ref name="name"/>. Such forward-slash-terminated named tags may precede the definition of the named reference.^[5]

In the following example, the same source is cited three times.

This is an example of multiple references to the same footnote.<ref name="multiple"/> Such references are particularly useful when citing sources, if different statements come from the same source.<ref name="multiple">Remember that when you refer to the same footnote multiple times, the text from the first reference is used.</ref> A concise way to make multiple references is to use empty ref tags, which have a slash at the end.<ref name="multiple">This text is superfluous, and won't show up anywhere. We may as well just use an empty tag.</ref> == Notes == <references />

The text above gives the following result in the article (see also Notes section below):

This is an example of multiple references to the same footnote.^[6]

Such references are particularly useful when citing sources, when different statements come from the same source.^[6]
A concise way to make multiple references is to use empty ref tags, which have a slash at the end.^[6]

One should be particularly careful when deleting one of multiple named references, because the footnote text will be deleted unless it is copied to another ref tag with the same name.

Citation templates

Text placed between <ref> and </ref> may be short notes or full bibliographic references, and may be formatted either by hand or with the assistance of templates. Instructions on available templates to help format bibliographic references may be found at Wikipedia:Citation templates. Use of such templates is not required; see WP:CITE.

Style recommendations

Avoid using Ibid or similar abbreviations in footnotes. Other editors who add new references to the article may not take the time to correct Ibid references broken by their addition. Furthermore, not all readers are familiar with the meaning of the term. If a reference is reused in more than one footnote, it is preferable to use the format "Smith, Short Title, 182" rather than "Ibid, 182", so as to avoid these problems, or use named references if appropriate.
Consider maintaining a separate bibliography/references section that gives full publication details for frequently cited sources, then you only need to cite the author, short title, and page number in specific notes, following Wikipedia:Citing sources. For an example see Johannes Kepler.
Internal links and wiki formatting work as normal within the text of the citation, like this: <ref>''[[Wikipedia]]'', [[18 March]], [[2007]].</ref> However, you cannot rely on the "pipe trick" to expand a link for you in ref text; you must type out [[George Clark (historian)|George Clark]], instead of just typing [[George Clark (historian)|]] and letting the software fill in the text after the pipe. See Help:Pipe_trick#Cite.php_footnotes_and_the_pipe_trick.
Do not use <ref> tags within templates. They are not numbered correctly. See m:Cite.php#Current_problems, and User:Pengo/pageusingref for an illustration of the issue. Ref tags may also not handle template parameters correctly.
References cannot be nested: <ref name="Ran1912">J. Random, 1912. Cited in <ref name="Foo2005"/></ref> does not render correctly.

Resizing references

Some editors make the references smaller. Although smaller text has several disadvantages, it is common with very long lists of references to substitute the basic <references /> tag with {{Reflist}}, which reduces the text size to 90%. {{Reflist}} should not be used with a "subst:". The underlying CSS class is "references-small", which may be used directly as <div class="references-small"><references /></div>. If this class is used to make other sections small for consistency (e.g. notes, references, see also, external links sections), the div tags must be opened and closed within each section.

A similar CSS class exists to create small footnotes in two (or optionally, three) columns, but this displays as a single column in some common browsers. If desired, use {{Reflist|2}} or the CSS class directly with <div class="references-2column"><references /></div>

Compatibility with other MediaWiki sites

As of late December 2005, the Cite.php extension to MediaWiki has been installed on all Wikimedia wikis. Other wikis that use the MediaWiki software may not have this extension installed, and therefore may be unable to display Cite.php footnotes. The Special:Version page on a MediaWiki wiki shows the installed extensions.

Technical details

See Meta:Cite/Cite.php for a technical explanation of the Cite.php extension on Meta-Wiki.

Converting citation styles

Converting citation styles should not be done without first gaining consensus for the change on the article's talk page.

A December 2005 ArbCom case ruled that the following scripts could no longer be used by a certain Wikipedian:

Wikipedia:Footnote3/numlink2note.pl, explained at Wikipedia talk:Footnote3/numlink2note.pl
Wikipedia:Footnote3/order-footnote.pl, explained at Wikipedia talk:Footnote3/order-footnote.pl

Similarly, individual users may be forbidden to "manually convert citation styles on any articles."

So, tread lightly, and seek consensus first, before converting citation styles. For example, when using (semi-)bot tools as listed below:

User:Cyde/Ref converter converts articles that use the {{ref}} and {{note}} system into the more recent m:Cite.php system;
Citation Tool diagnoses and fixes sequencing and duplication errors in m:Cite.php references. In the future, Citation Tool may (optionally) enable user-guided conversion of some or all of the <ref> numbered citations to named notes using the footnote3 template technology (which includes Harvard references).

CAUTION: do not edit-war with automated tools that convert in opposing directions.

Notes

^ The Wikipedia:Footnote3 system created footnotes with the {{ref}}/{{note}} and the {{ref_label}}/{{note_label}} pairs of templates. The system is still operational, and may be encountered on many Wikipedia pages.
^ ^a ^b This footnote is used as an example in the "How to use" section.
^ ^a ^b ^c ^d ^e This is the convention used in the Chicago Manual of Style.
^ "Note reference numbers. The superior numerals used for note reference numbers in the text should follow any punctuation marks except the dash, which they precede. The numbers should also be placed outside closing parentheses." The Chicago Manual of Style, 14th ed. 1993, Clause 15.8, p. 494.
^ Wikipedia Signpost. November 13, 2006.
^ ^a ^b ^c Remember that when you refer to the same footnote multiple times, the text from the first reference is used. Cite error: The named reference "multiple" was defined multiple times with different content (see the help page).

Additional references that are not created with the extension (as per WP:CITE) do not continue the numbering.

[1] The Wikipedia:Footnote3 system created footnotes with the {{ref}}/{{note}} and the {{ref_label}}/{{note_label}} pairs of templates. The system is still operational, and may be encountered on many Wikipedia pages.

[example-2] This footnote is used as an example in the "How to use" section.

[location-3] This is the convention used in the Chicago Manual of Style.

[4] "Note reference numbers. The superior numerals used for note reference numbers in the text should follow any punctuation marks except the dash, which they precede. The numbers should also be placed outside closing parentheses." The Chicago Manual of Style, 14th ed. 1993, Clause 15.8, p. 494.

[5] Wikipedia Signpost. November 13, 2006.

[multiple-6] Remember that when you refer to the same footnote multiple times, the text from the first reference is used. Cite error: The named reference "multiple" was defined multiple times with different content (see the help page).

[1]

[2]

[3]

[4]

[5]

[6]

@@ Line 22: / Line 22: @@
 This page itself uses footnotes, such as the one at the end of this sentence.<ref name="example">This footnote is used as an example in the "How to use" section.</ref> If you view the Wikicode of this page by clicking "Edit this page", you can see a working example of footnotes. For the purpose of adding references, the more recent cannot be mixed on a page with the old [[Wikipedia:Footnote3|Footnotes3]] format—you must pick one or the other. It is possible, however, to use the template system to e.g. separate content notes and references when that is deemed a good idea (this is often the case when content notes must be themselves cited, see, for example, [[Alcibiades]]).
-===Where to place reference tags===
+===Where to place ref tags===
+Place a ref tag at the end of the term, phrase, sentence, or paragraph to which the note refers.<ref name="location">This is the convention used in the Chicago Manual of Style.</ref>
-{{main|Wikipedia:Citing sources#Placement of footnote reference tags}}
-Some words, phrases or facts must be referenced mid-sentence, while others are referenced at the end. Frequently, a reference tag will coincide with punctuation and many editors put the reference tags after punctuation (except dashes), as is recommended by the Chicago Manual of Style (CMoS).<ref name="location">"''Note reference numbers.'' The superior numerals used for note reference numbers in the text should follow any punctuation marks except the dash, which they precede. The numbers should also be placed outside closing parantheses." (''The Chicago Manual of Style'', 14th ed. 1993, Clause 15.8, p. 494)</ref> Some editors prefer the style of those journals, like ''[[Nature (journal)|Nature]],'' which place references before punctuation.   Each article should be internally consistent, but editing solely to change from one style to another throughout an article is deprecated unless there is a [[wikipedia:consensus|consensus]] to make the change.''
+When placed at the end of a clause or sentence the ref tag should be directly after the punctuation mark without an intervening space,<ref name="location"/> in order to prevent the reference number wrapping to the next line.<ref name="location"/> The same is true for successive ref tags.<ref name="example"/><ref name="location"/> The exception is a dash<ref name="location"/>—which should follow the ref tag.  This is the format recommended by the [[Chicago Manual of Style]].<ref>"''Note reference numbers.'' The superior numerals used for note reference numbers in the text should follow any punctuation marks except the dash, which they precede. The numbers should also be placed outside closing parentheses." ''[[The Chicago Manual of Style]]'', 14th ed. 1993, Clause 15.8, p. 494.</ref>
 Example: