Wikipedia:Wikipedia in brief

Wikipedia aims to be a neutral compilation of verifiable, established facts.

This means:

Neutral: Wikipedia does not judge or advocate specific views or opinions, or make determinations on "correctness". Where differing views exist, they are presented objectively, without bias or undue weight. Balance derives from reliable sources, not personal judgment.
Compilation: Wikipedia is an encyclopedia, consisting of articles written in a particular style. There is a process which advances articles to our goal.
Verifiable: Information must be realistically verifiable by others. This is generally done by citing from reliable sources.
Established: Original ideas, interpretations, or research cannot be verified, and thus are inappropriate for Wikipedia. Wikipedia is not a primary source; it strives to be a tertiary source.
Facts: Wikipedia documents facts; it does not offer editorial opinions. Articles state the important views which exist, and who holds them ("facts about opinions").

See also[edit]

Wikipedia:Administration – Discuses both the human administrative structure of Wikipedia, and its non-human components.
Wikipedia:Biographies of living persons – About how editors must take particular care when adding information about living persons to any Wikipedia page.
Wikipedia:Purpose – Describes Wikipedia's motive for being.
Wikipedia:Here to build an encyclopedia – About how Wikipedians are here to build an encyclopedia, i.e., a neutral public reference work on certain topics.
Wikipedia:Five pillars – The fundamental principles of Wikipedia summarized in five "pillars".
Wikipedia:The rules are principles – About how policies and guidelines exist only as rough approximations of their underlying principles.
Wikipedia:What Wikipedia is not – The page outlines certain things that Wikipedia is not.