Wikipedia:Attribution was created to serve as a combination of Wikipedia:Verifiability, Wikipedia:No original research and Wikipedia:Reliable sources. It was believed that consensus for such a merger was reached, but that has been called into question. The long-term resolution of this issue is presently under discussion.

Wikipedia articles should be based on reliable, published sources. This page is a guideline, not a policy, and is mandatory only insofar as it repeats material from policy pages. The relevant policies on sources are Wikipedia:Verifiability, Wikipedia:No original research, and Wikipedia:Neutral point-of-view.

Wikipedia:Verifiability says that any material that is challenged or likely to be challenged needs a source, as do quotations, and the responsibility for finding a source lies with the person who adds or restores the material. Unsourced or poorly sourced edits may be challenged and removed at any time. Sometimes it is better to have no information at all than to have information without a source. See that page for more information about Wikipedia's policy on sourcing.

Reliable sources are credible published materials with a reliable publication process; their authors are generally regarded as trustworthy, or are authoritative in relation to the subject at hand.

The reliability of a source depends on context; what is reliable in one topic may not be in another. A world-renowned mathematician may not be a reliable source on topics of biology. However a statistician commenting on the statistical methods used in a peer reviewed biology article would qualify as a reliable source. In general, a topic should use the most reliable sources available to its editors.

Sources are used:

• To support an assertion made in an article. Sources used in this manner should be directly referenced for the point that is being supported.
• To give credit to the source, to avoid the appearance of plagiarism or copyright violations. See Wikipedia:Copyrights.

Using reliable sources assures the reader that what is being presented meets the Wikipedia standards for verifiability and originality. Accurate citation allows the reader to go to those sources and gives appropriate credit to the author of the work.

If all the sources for a given statement or topic are of low reliability, the material may not be suitable for inclusion in Wikipedia.

Wikipedia welcomes material written by scientists, scholars, and researchers, particularly material published by peer-reviewed journals. However, these may be outdated by more recent research, or may be controversial in the sense that there are alternative scholarly and non-scholarly treatments. Wikipedia articles should therefore ideally rely on all majority and significant-minority treatments of a topic, scholarly and non-scholarly, so long as the sources are reliable.

Certain red flags should prompt editors to examine the sources for a given claim.

• Surprising or apparently important claims that are not widely known.
• Surprising or apparently important reports of recent events not covered by reliable news media.
• Reports of a statement by someone that seems out of character, embarrassing, controversial, or against an interest they had previously defended.
• Claims not supported or claims that are contradicted by the prevailing view in the relevant academic community. Be particularly careful when proponents say there is a conspiracy to silence them.

Exceptional claims should be supported by multiple reliable sources, especially regarding scientific or medical topics, historical events, politically charged issues, and biographies of living people.

Claims of consensus must be sourced. The claim that all or most scientists, scholars, or ministers hold a certain view requires a reliable source. Without it, opinions should be identified as those of particular, named sources.

See No original research: Primary, secondary, and tertiary sources

See Wikipedia:Biographies of living persons

See Verifiability: Self-published sources (online and paper)

See Wikipedia:Convenience links#Reliability

See Wikipedia:Reliable sources/examples for examples of the use of statistical data, advice by subject area (including history, physical sciences, mathematics and medicine, law, Business and Commerce, popular culture and fiction), and the use of electronic or online sources.

• Wikipedia:Check your facts, essay
• Wikipedia:Common knowledge, essay
• Wikipedia:Independent sources, essay
• Wikipedia:WikiProject Fact and Reference Check
• Wikipedia:Verifiability
• Wikipedia:No original research
• Wikipedia:Citing sources

• How to Read a Primary Source, Reading, Writing, and Researching for History: A Guide for College Students, Patrick Rael, 2004.
• How to Read a Secondary Source, Reading, Writing, and Researching for History: A Guide for College Students, Patrick Rael, 2004.