Wikipedia:Reliable sources

Wikipedia articles should be based on reliable, published sources, making sure that all majority and significant minority views that have appeared in those sources are covered (see Wikipedia:Neutral point of view). If no reliable sources can be found on a topic, Wikipedia should not have an article on it.

This guideline discusses the reliability of various types of sources. The policy on sourcing is Wikipedia:Verifiability, which requires inline citations for any material challenged or likely to be challenged, and for all quotations. The verifiability policy is strictly applied to all material in the mainspace—articles, lists, and sections of articles—without exception, and in particular to biographies of living persons, which states:

Contentious material about living persons (or, in some cases, recently deceased) that is unsourced or poorly sourced—whether the material is negative, positive, neutral, or just questionable—should be removed immediately and without waiting for discussion.

In the event of a contradiction between this guideline and our policies regarding sourcing and attribution, the policies take priority and editors should seek to resolve the discrepancy. Other policies relevant to sourcing are Wikipedia:No original research and Wikipedia:Biographies of living persons. For questions about the reliability of particular sources, see Wikipedia:Reliable sources/Noticeboard.