View source for Wikipedia:Citing sources

===Variation in citation methods <span id="Style variation and consistency"></span>===
{{shortcut|WP:CITEVAR|WP:WHENINROME}}
Editors should not attempt to change an article's established citation style, merely on the grounds of personal preference or to make it match other articles, without first seeking [[WP:Consensus|consensus]] for the change.{{notetag|The arbitration committee [[Wikipedia:Requests for arbitration/Sortan#Preferred styles|ruled in 2006]]: "Wikipedia does not mandate styles in many different areas; these include (but are not limited to) American vs. British spelling, date formats, and citation style. Where Wikipedia does not mandate a specific style, editors should not attempt to convert Wikipedia to their own preferred style, nor should they edit articles for the sole purpose of converting them to their preferred style, or removing examples of, or references to, styles which they dislike."}}

As with [[WP:ENGVAR|spelling differences]], it is normal practice to defer to the style used by the first major contributor or adopted by the consensus of editors already working on the page, unless a change in consensus has been achieved. If the article you are editing is already using a particular citation style, you should follow it; if you believe it is inappropriate for the needs of the article, seek consensus for a change on the talk page. If you are the first contributor to add citations to an article, you may choose whichever style you think best for the article. However, [[Special:PermanentLink/976895063#Deprecate parenthetical citations|since 5 September 2020]], inline [[#Parenthetical referencing|parenthetical referencing]] is a deprecated citation style on English-language Wikipedia.

If all or most of the citations in an article consist of [[WP:bare URLs|bare URLs]], or otherwise fail to provide needed bibliographic data{{snd}} such as the name of the source, the title of the article or web page consulted, the author (if known), the publication date (if known), and the page numbers (where relevant){{snd}} then that would not count as a "consistent citation style" and can be changed freely to insert such data. The data provided should be sufficient to uniquely identify the source, allow readers to find it, and allow readers to initially evaluate a source without retrieving it.

====Generally considered helpful====
The following are standard practice:
* improving existing citations by adding missing information, such as by replacing bare URLs with full bibliographic citations: an improvement because it aids [[WP:Verifiability|verifiability]], and fights [[WP:Link rot|link rot]];
* replacing some or all general references with inline citations: an improvement because it provides more verifiable information to the reader, and helps maintain text–source integrity;
* imposing one style on an article with inconsistent citation styles (e.g., some of the citations in footnotes and others as parenthetical references): an improvement because it makes the citations easier to understand and edit;
* fixing errors in citation coding, including incorrectly used template parameters, and <code><nowiki><ref></nowiki></code> markup problems: an improvement because it helps the citations to be parsed correctly;
* combining duplicate citations {{crossref|(see {{section link||Duplicate citations}}, above)}};
* converting [[WP:PAREN|parenthetical referencing]] to an acceptable referencing style;
* replacing opaque [[WP:NAMEDREFS|named-reference]] names with conventional ones, such as "Einstein-1905" instead of ":27"; and
* making citations added by other editors match the existing style (if any).  Do not revert someone else's contribution merely because the citation style doesn't match.  [[WP:SOFIXIT|If you know how to fix it, then fix it]].

====To be avoided====
When an article is already consistent, avoid:
* switching between major citation styles or replacing the preferred style of one academic discipline with another's – except when moving away from deprecated styles, such as [[#Parenthetical referencing|parenthetical referencing]];
* adding citation templates to an article that already uses a consistent system without templates, or removing citation templates from an article that uses them consistently;
* changing where the references are defined, e.g., moving [[WP:LDRHOW|reference definitions in the reflist]] to the prose, or moving reference definitions from the prose into the reflist.

====Parenthetical referencing====
{{redirect|WP:PARENTHETICAL|guidelines on the use of parentheses (round brackets)|WP:Manual of Style#Brackets and parentheses}}
{{shortcut|WP:PAREN}}
<!--{{see|Wikipedia:Parenthetical referencing}}-->

Since September 2020, inline [[parenthetical referencing]] has been [[Special:PermanentLink/976895063#Deprecate parenthetical citations|'''deprecated''' on Wikipedia]]. This includes short citations in parentheses placed ''within the article text itself'', such as {{!xt|(Smith 2010, p. 1)}}. This does not affect short citations that use {{tag|ref|o}} tags, which are not inline parenthetical references; see the [[#Short and full citations|section on short citations]] above for that method. As part of the deprecation process in existing articles, discussion of how best to convert inline parenthetical citations into currently accepted formats should be held if there is objection to a particular method.

This should no longer be used, and should be replaced with footnotes if encountered:
{{block indent|style=background: white; padding: 1em; border: 1px solid #999;|1={{cross}}
The Sun is pretty big (Miller 2005, p. 1), but the Moon is not so big (Brown 2006, p. 2). The Sun is also quite hot (Miller 2005, p. 3).
{{fake heading|References}}
* Brown, R. (2006). "Size of the Moon", ''Scientific American'', 51 (78).
* Miller, E. (2005). ''The Sun'', Academic Press.
}}