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.
This is an essay.
It contains the advice or opinions of one or more Wikipedia contributors. This page is not an encyclopedia article, nor is it one of Wikipedia's policies or guidelines, as it has not been thoroughly vetted by the community. Some essays represent widespread norms; others only represent minority viewpoints.
|This page in a nutshell: Although citing sources is an important part of editing Wikipedia, there is no need to cite information that is already obvious.|
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.