On Wikipedia, an inline citation is generally a citation in a page's text placed by any method that allows the reader to associate a given bit of material with specific reliable source(s) that support it. The most common method is numbered footnotes within the text, but other forms are also used on occasion.

Inline citations are often placed at the end of a sentence or paragraph. Inline citations may refer to electronic and print references such as books, magazines, encyclopedias, dictionaries and Internet pages. Regardless of what types of sources are used, they should be reliable; that is, credible published materials with a reliable publication process whose authors are generally regarded as trustworthy or authoritative in relation to the subject at hand. Verifiable source citations render the information in an article credible to researchers.

The opposite of an inline citation is what the English Wikipedia calls a general reference. This is a bibliographic citation, often placed at or near the end of an article, that is unconnected to any particular bit of material in an article, but which might support some or all of it. It is called a "general reference" because it supports the article "in general", rather than supporting specific sentences or paragraphs.

Inline citations and Wikipedia

Many Wikipedia articles contain inline citations: they are required for featured articles, good articles, and A-class articles. There are many ways to add inline citations to an article. Each is acceptable under Wikipedia's citation style guideline, but a single article should use only one type.

Ref tags

Main page: Help:Footnotes

Creating footnotes using "<ref>" tags is by far the most popular method for citing sources. It can be used for both bibliographic citations and also for explanatory notes. This method automatically arranges the references presented in an article through the use of opening and closing ref tags: <ref> and </ref>. Information placed between the two tags forms the footnote. Either standard wiki markup or citations templates can be used to format bibliographic citations. Either the multifeatured ((Reflist)) template or the simple <references /> code must be present on the page to indicate where the footnote should appear. Footnotes will not appear in the list unless they are placed somewhere above the ((Reflist)) or <references />.

If multiple citations for the same source are included in the article, and you are using <ref> tags, you can name the footnote to link to the same note repeatedly. To do this, add name="X" to the first <ref> tag, so that it looks like this: <ref name="X">.[1] As before, this will generate a number at the end of the sentence. Replace the "X" with any word to denote which source the computer should jump to when multi-linking like this.[1] Notice that this method of citing creates the same number for each entry cited with a <ref name="X"> citation. You can reuse the footnote repeatedly merely by typing the named <ref> tag with a slash following the name, like this: <ref name="X" />.

"Reference" and "Note" templates

Main page: Wikipedia:Footnote3

This is an older citation method which is still sometimes used for citations and/or for explanatory text. This template creates superscript numbers in a text which, when clicked on, direct the reader to the citation at the bottom of the page.

Both the reference template and the note template consist of two parts: ((ref|word reference)) and ((note|word reference)). If you wish to use these templates, then begin by placing the ((ref| )) template in the article where you wish to cite the presented information. After the "|" include a small word reference for the citation; this will tell the computer which link it should jump to when a reader clicks on the article citation.

Here's a working example: to cite the book The Navy, insert a reference tab—((ref| ))—at the end of this sentence and place the word "Navy1" after the vertical line so that it looks like this:((ref|Navy1)).[1] Notice how a small number now appears at the end of the previous sentence; this contains the information that will be cited in the reference section. Click on the small number at the end of the previous sentence to continue with the example.

Although the default formatting matches standard <ref>...</ref> tags, it also allows you to use any letter, number, or symbol you choose. As a result, this system is popular with people who want to manually number or format the superscripted footnote markers for citations and/or explanatory notes. For example, using this system, you can easily produce a footnote that looks like this or That. For more information about using this method, see Template:Ref/doc.

Hyperlinking/embedded links

Further information: Wikipedia:Citing sources § Avoid embedded links

In the early days of Wikipedia, links to other websites were allowed. For example, a link to the biography of William Shakespeare on the Oxford Dictionary of National Biography could be created like this:

  "[https://www.oxforddnb.com/view/article/25200  William Shakespeare]"

which creates a link like this: "William Shakespeare" Or created like this:

  "William Shakespeare.[https://www.oxforddnb.com/view/article/25200]"

which creates a link like this: "William Shakespeare.[2]"

This type of hyperlinking, when not inside a ref..tag pair, has long since been deprecated (see Citing sources § Avoid embedded links).

Links to sister projects

Main pages: Wikipedia:Wikimedia sister projects and Wikipedia:Manual of Style/Layout § Links to sister projects

Just as an internal link can be created like this [[William Shakespeare]] links to sister projects can be created similarly.

For example, Wikisource contains the text of a letter from Oliver Cromwell to the Speaker of the English Parliament

 [[s:Cromwell letter to John Bradshaw]]

This might appear in a sentence like this:

After the storming of Drogheda, Oliver Cromwell wrote a letter to John Bradshaw.

This is not adequate as an inline citation because it is not obvious to the reader that there is any form of inline citation to support the sentence. To fulfill that requirement it would be necessary to add an inline citation that specifies the additional information, like where and when the letter was published, that is necessary to identify exactly which letter is indicated.

Manual citations

Occasionally, editors will hand-number sources. This is very easy to create—an editor can just type a number or other symbol at the end of the relevant passage, and a matching number before the bibliographic citation—but it is often difficult to maintain if the article is expanded or rearranged.

Some lists, such as Line of succession to the British throne, use a similar system with a code letter or word to indicate which source the information is taken from.

Legal citations

Some fields provide full citations inline, without a unified list of sources. For example, a standard legal citation system that refers to the Griswold v. Connecticut case will simply type Griswold v. Connecticut, 381 U.S. 479, 480 (1965). at the end of the material supported by the case.

Similarly, some scientific citation systems provide references by typing only the abbreviated name of the journal, the volume number, and the page numbers at the end of a passage.

Both of these systems are valid inline citation formats—they both permit the reader to identify which source supports which material in the article—but they are uncommon on Wikipedia.

Parenthetical reference

Main page: Wikipedia:Parenthetical referencing

Inline parenthetical referencing is a citation system in which in-text citations are made using parentheses. Various formats are seen, e.g., (Author, date) or (Author, date:page), etc. Such citations are normally typed in plain text and appear before punctuation. The full bibliographic citation is then typed at the bottom of the article, usually in alphabetical order.

This citation system was deprecated by a community discussion and is no longer used in new articles. If you run across this format, whether in an old article or in a new contribution from an editor who hasn't yet learned other styles, please help by converting it to a non-deprecated style. If you don't know how to fix it yourself, then you can tag the article with ((Inline parenthetical referencing|date=July 2024)) to help more experienced editors find it.

In-text attribution

In-text attribution sometimes involves naming the source in the sentence itself:

Alice Jones said in her 2008 book, The Sun Is Really Big, ...

This is technically a valid inline citation for Wikipedia's purposes—it permits the reader to identify which source supports the material, right there in the line of text—but it is normally used in addition to some other system of inline citation for quotations, close paraphrasing, and anything contentious or distinctive, where the editor wants to draw attention to the source's name in the article. This is most commonly used for very widely recognized classical sources, such as Shakespeare's plays, the Bible, or ancient Greek and Roman philosophers.

When you must use inline citations

All content in articles must be verifiable. Wikipedia policy requires an inline citation to a reliable source specifically for the following four types of statements:

Type of statement Policy requiring inline citation
Direct quotations Wikipedia:Verifiability
Any statement that has been challenged (e.g., by being removed, questioned on the talk page, or tagged with ((citation needed)), or any similar tag) Wikipedia:Verifiability
Any statement that you believe is likely to be challenged. Wikipedia:Verifiability
Contentious material, whether negative, positive, or neutral, about living persons Wikipedia:Biographies of living persons

Other policies, notably the copyright violations policy, prohibit the inclusion of some information, such as too-close paraphrasing, even if the material is supplied with an inline citation to a reliable source.

Our sourcing policies do not require an inline citation for any other type of material, although it is typical for editors to voluntarily exceed these minimum standards. However any material lacking an inline citation to a reliable source that directly supports the material may be removed and should not be restored without an inline citation to a reliable source. Substantially exceeding them is a necessity for any article to be granted good or featured article (or list) status. The featured article criteria, for example, require that articles seeking to exemplify Wikipedia's very best work must be "well-researched," defined as a "thorough and representative survey of the relevant literature", presented by "consistently formatted inline citations using footnotes". If you can't find the source of a statement without an inline citation after a good-faith look, ask on the talk page, or request a citation. As of 2022, there was no specified amount of inline citation that an article must have before being eligible for nomination as a Featured Article, Good Article, or (when applicable) A-Class article, and no particular style is favored over any other.

Technically, if an article contains none of these four types of material, then it is not required by any policy to name any sources at all, either as inline citations or as general references. For all other types of material, the policies require only that it be possible for a motivated, educated person to find published, reliable sources that support the material, e.g., by searching for sources online or at a library. However, it is rare for articles past the stub stage to contain none of these four types of material.

Editors are expected to use good judgment when determining whether material has been challenged. For example, section blanking may be considered vandalism, rather than a demand for inline citations.

Citation density

Wikipedia does not have a "one inline citation per sentence" or "one citation per paragraph" rule, even for featured articles. Wikipedia requires inline citations based on the content, not on the grammar and composition elements. Some articles (e.g., articles about controversial people) will require inline citations after nearly every sentence. Some sections (e.g., dense technical subjects) may even require more than one inline citation per sentence. Others may not require any inline citations at all.

For example, one inline citation is sufficient for this paragraph:

Education researcher Mary Jones says that there are three kinds of students. The first group is made up of students who do their homework as soon as they receive the assignments. The second group contains students who do their homework at the last possible second. The third group is composed of students who did not realize that they were supposed to do the assignment.[1]

Everything in that paragraph deals with the same, single subject from the same source and can therefore be supported by a single inline citation. The inline citation could be placed at any sensible location, but the end of the paragraph is the most common choice. If a subsequent editor adds information from another source to this paragraph, then it is the subsequent editor's job to organize the citations to make their relationship between the text and the sources clear, so that we maintain text-source integrity.

Text–source integrity

Further information: WP:INTEGRITY and Wikipedia:When to cite

Using inline citations, even for statements that are not absolutely required to have inline citations, helps Wikipedia maintain text–source integrity. Using inline citations allows other people to quickly determine whether the material is verifiable.

The best distance between the material and the citation is a matter of judgment. If a word or phrase is particularly contentious, an inline citation may be added next to it within a sentence, but adding the citation to the end of the sentence or paragraph is usually sufficient. Editors should exercise caution when adding to or rearranging material to ensure that text-source relationships are maintained.

References/Notes section

This section is where the bibliographic citations to the reliable sources that were used to build the article content are presented. The most popular choice for the section heading's name is "References"; other articles use "Notes", "Footnotes", or "Works cited" (in diminishing order of popularity). Several alternate titles ("Sources", "Citations", "Bibliography") may also be used, although each is problematic: "Sources" may be confused with source code in computer related articles or ways to acquire a product; "Citations" may be confused with official awards or a summons to court; "Bibliography" may be confused with a list of printed works by the subject of a biography.

Sometimes more than one section is needed to organize the citations. For example, articles using shortened citations may use one section for full bibliographic citations and a separate section for shortened citations.

A reference section should not be confused with external links or further reading sections, neither of which contain sources that were used to build the article content. For more information and the relevant style guide on reference sections, see Wikipedia:Citing sources.

Reference section and "Reference" and "Note" templates

^ Notice the caret to the far left, this is the result of the ((note| reference. At the moment, the note reference looks like this: ((note|Navy1)). Recall that the above link you clicked on to get here was titled ((ref|Navy1)), so this is the correct corresponding link. To create the underlined arrows like the one that took you here place a ((note)) template followed by the correct word description for the given information. Place the reference material you are referring to after the completed ((note)) template, and ensure that the ((ref)) and ((note)) templates are correctly linking to each other by checking the spelling. There are several templates that can help with the citation format. For example, the full reference for the Navy citation should read as follows:

     ^ Naval Historical Foundation. The Navy. Barnes & Noble Inc, China ISBN 0-7607-6218-X

Inline citations that make use of the reference and note templates do not generate numbers for the corresponding links; this can be corrected by placing a "#" before inserting the template text, as shown below:

# ((note|Navy1)) Naval Historical Foundation. ''The Navy''. Barnes & Noble Inc, China ((ISBN|0-7607-6218-X))

This will generate a full-sized number which should correspond with the number clicked on for an information's source, as in the example below:

  1. ^ Naval Historical Foundation. The Navy. Barnes & Noble Inc, China ISBN 0-7607-6218-X

In the case of the above example, the number 1. now appears before the citation to the book The Navy. Recall that the number you clicked on to get here was a 2, so the link and its number do not correspond; in this case, it is because of the hyperlink discussed in the previous section. Since this article exists merely to explain the function of the reference and note templates this is not of concern; however, if this problem occurs in an actual article it means that something has caused the numbers and sources to mismatch.

Reference section and footnotes

  1. ^ a b Notice how the letters now appear at the left hand side in front of the link. This is because each of these two entries share the same name, in this case "Example", and have been configured to link to one spot to save room.

If you are using the Footnotes method (the <ref> and </ref> tags), all you have to do when creating a reference section is insert the simple <references /> code or the ((reflist)) template, which automatically generates a list of references for the inline citations provided in the article.

See also