Yes, the sky is blue: There is such thing as over-citing.
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This Wikipedia essay, originally titled You don't need to cite that the sky is blue was started in 2007. You may edit the essay, but please do so at WP:BLUE and not on The Signpost.
Which of these things needs a citation?
Which of these things needs a citation?

Verifiability is an important and core policy of Wikipedia. Article content should be backed up by reliable sources wherever needed to show that the presentation of material on Wikipedia is consistent with the views that are presented in scholarly discourse or the world at large. Such sources help to improve the encyclopedia.

However, many editors misunderstand the citation policy, seeing it as a tool to enforce, reinforce, or cast doubt upon a particular point of view in a content dispute, rather than as a means to verify Wikipedia's information. This can lead to several mild forms of disruptive editing, which are better avoided. Ideally, common sense would always be applied, but Wiki-history shows this is unrealistic. Therefore, this essay gives some practical advice.

Not citing common knowledge and not providing bibliographic entries for very famous works is also consistent with major academic style guides, such as The MLA Style Manual and the APA style guide.

Pedantry, and other didactic arguments

Sometimes editors will insist on citations for material simply because they dislike it or prefer some other material, not because the material in any way needs verification. For example, an editor may demand a citation for the fact that most people have five digits on each hand (yes, this really happened).[1] Another may decide that the color of the sky is actually aqua rather than blue, pull out an assortment of verifiable spectrographic analyses and color charts to demonstrate that this position is actually correct, and follow that with a demand that other editors provide equivalent reliable sources for the original statement that the sky is in fact blue. While there are cases where this kind of pedantic insistence is useful and necessary, often it is simply disruptive, and can be countered simply by pointing out that there is no need to verify statements that are patently obvious. If the alternative proposition merits inclusion in the article under other policies and guidelines it should of course be included, but it should in no way be given greater prominence because it is sourced.


Wikipedia has several templates for tagging material that needs verification: inline templates for particular lines, section templates, and article templates. See Wikipedia:Template messages. Sometimes editors will go through an article and add dozens of the inline tags, along with several section and article tags, making the article essentially unreadable (see WP:TAGBOMBING). As a rule, if there are more than 2 or 3 inline tags they should be removed and replaced with a section tag; if there are more than 2 section tags in a section they should be removed and replaced with a single 'Multiple issues' tag. If there are more than two or three sections tagged, those tags should be removed, and the entire article should be tagged.

Verification tags should not be used in a POINTed fashion. Use only those tags necessary to illustrate the problem, and discuss the matter in detail on the talk page.


Citations should be evaluated on the qualities they bring to the article, not on the quantity of citations available. The first 1 or 2 citations supporting a given point are informative; extra citations after that begin to be argumentative. Keep in mind that the purpose of a citation is to guide the reader to external sources where the reader can verify the idea presented, not to prove to other editors the strength of the idea. Extra sources for the same idea should be added to 'Further Reading', 'See Also' or 'External Sources' sections at the bottom of the page, without explicitly being cited in the text.

Citing everything

A common misconception when improving an article, particularly towards Good Article status, is that everything must be cited to an inline source, which leads to comments such as "the end of paragraph 3 is uncited", without specifying why that is an issue. In fact, the Good Article criteria merely state that inline citations are required for "direct quotations, statistics, published opinion, counter-intuitive or controversial statements that are challenged or likely to be challenged, and contentious material relating to living persons". While that covers much, most, or possibly even (in the case of biographies of living people) all content in an article, it does not imply that you must cite everything everywhere for every single article, period.

See also


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  • Extra cites can also be housed in the talk page, where they may prove useful in the future should cites in the article become unverifiable, AfD notability, or other reasons. -- GreenC 00:23, 28 March 2022 (UTC)[reply]
  • I mildly disagree with the section about over-tagging. I happen to edit LOTS of under-edited articles and quite often I see sections with many footnotes, but over time people added some texts in-between, and it is very hard to recognize which statements do require extra verification. Of course, if most of the section is unreferenced, then the section-wide hatnote is reasonable, but when there are plenty of references, the questionable statements IMHO deserve direct indication. So instead of removing "cn" tags, I would recommend to invent a less intrusive text of the tag.Loew Galitz (talk) 02:29, 30 March 2022 (UTC)[reply]
  • I disagree also. "Frank Ito invented the caps lock key" may not be counter-intuitive or controversial but it's still wrong. Verifiability requires that we be able to point to where we got a particular fact from. I know some editors prefer just deleting uncited text rather than adding tags, and it's not a bad idea. Often it is easier to completely rewrite an unreferenced article than to provide references for. Hawkeye7 (discuss) 05:09, 31 March 2022 (UTC)[reply]
  • It's a worthy attempt, but much has changed since 2007. A simple riposte is that any statement may be challenged at any time, and eventually everything will be. The idea that you go through GA with uncited statements that get challenged later – during the DYK process, perhaps, hmm? ... or even waiting to get a really thorough pasting at FAC, is anyone seriously advising that? – is I'm afraid at least 15 years behind the times. More to the point, it invites fly-by editing and the addition of unverified, and often frankly unverifiable claims, in other words WP:OR. It anything is a wrong direction, that'd be it. No, the encyclopedia is built, brick by brick, of established, verifiable statements. But actually, the "sky is blue" title is deceptively misleading. If we are writing an article about atmospheric physics, we might well have a whole section cited to many scholarly sources explaining exactly why the sky is blue, it is a deep and quite challenging question to explain to non-physicists. In an article on flower-arranging, we will not state "and the sky is blue", we will perhaps say "Against a plain backdrop like a blue sky, ..." and the claim about the way the arrangement looks will be cited, while the blueness of the sky will then certainly pass review without a citation of its own. So, the article is, I suggest, conflating two quite different things: specific claims (citation required) and passing mentions inside cited statements (no specific citation needed). Chiswick Chap (talk) 08:17, 31 March 2022 (UTC)[reply]
  • About the WP:Good article thing: the person who reviews a nomination assumes the responsibility of ensuring that the article meets the WP:Good article criteria, one of which (2c) is that it contains no original research, before passing. This means assuming the responsibility of ensuring that any uncited statements do not represent WP:Original research. With that in mind, I don't think it's unreasonable to ask that all content be cited in an article that is nominated for WP:Good article status. TompaDompa (talk) 15:59, 2 April 2022 (UTC)[reply]
  • The following is factually incorrect: "In fact, the Good Article criteria merely state that inline citations are required for 'direct quotations, statistics, published opinion, counter-intuitive or controversial statements that are challenged or likely to be challenged, and contentious material relating to living persons'". The relevant GA criterion (2b) actually states that, for a GA, "all inline citations are from reliable sources, including those for direct quotations, statistics, published opinion, counter-intuitive or controversial statements that are challenged or likely to be challenged, and contentious material relating to living persons". These are very different statements: "inline citations are required for..." versus "inline citations are from...". Based on WP:VERIFY (which GA criteria 2 start from), it's entirely reasonable for a GA reviewer to require a citation for everything that's asserted in an article, beyond the self-evident. EddieHugh (talk) 14:05, 3 April 2022 (UTC)[reply]