Wikipedia:Content policies and guidelines in a nutshell

Articles appropriate for this encyclopedia, cite verifiable claims from reliable sources (in proportion), without presenting our own claims.

Verifiability
Claims should come from published sources that can be verified by other Wikipedia editors.

Reliable sources
Verifiable claims should be based on references released by established experts and/or publishers with editorial oversight that have a reputation for fact-checking and accuracy.

Citing sources
Citing verifiable reliable sources is necessary for editors to verify the claims and assess the reliability of the references.

Neutral point of view
Wikipedia articles should present the claims and opinions appearing in the published body of reliable sources, fairly, proportionately, and as far as possible without editorial bias.

No original research
Claims must be verifiable in reliable references; consequently, editors may not insert their opinion or analysis of a subject into Wikipedia articles, explicitly or through presentation.