Wikipedia:You don't need to cite that the sky is blue

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 forms of mildly disruptive editing which are better avoided. Ideally, common sense would always be applied, but site 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.

Since all material that is either challenged or likely to be challenged must be cited, if someone else is already challenging material as false or misleading, then it needs an inline citation. Remember to assume good faith and consider that something that may be obvious to you may not be obvious to them, and that many things that "everyone knows" turn out to be false.

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 to verify that most people have five digits on each hand. Another may insist that the color of the sky is aqua rather than blue, while providing spectroscopic analyses as part of an assortment of verifiable evidence to support their position. Simultaneously, they demand that other editors show equivalent support in reliable sources for the claim that the sky is in fact blue. While there are times when this insistent attention to detail is useful or necessary, it is often simply disruptive and can be dismissed, as there is no need to verify statements that are obvious. Additional claims besides the obvious ones may merit inclusion according to site policies and guidelines, but they should in no way be given greater prominence because they happen to be sourced.

Over-tagging
Wikipedia has several templates for tagging material that needs verification: inline templates for particular lines, section templates, and article templates. See 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.

Over-citing
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.

Wikipedia guidelines

 * Common knowledge
 * Common knowledge

Wikipedia user essays

 * Wikipedia:You do need to cite that the sky is blue, the opposing essay
 * Likely to be challenged
 * Must I add a citation?
 * The Pope is Catholic
 * Don't be a WikiBigot
 * Wisps' Law
 * Why most sentences should be cited
 * You don't need a weatherman to know which way the wind blows
 * Verifiability, not truth, for when a reliable source claims the sky is bright green
 * Verifiability, not truth, for when a reliable source claims the sky is bright green

Related articles

 * Judicial notice, a legal rule that allows irrefutable, well-known facts to be introduced into evidence
 * Argumentum ad populum
 * Common knowledge