A tag for questions about the community wiki feature (regardless of whether or not the questions themselves are community wiki).

Community Wiki is a flag that can be applied to answers (and sometimes questions) which lowers the barrier for editing and prevents any rep gain/loss from voting.

See also:

An answer can be made community wiki by the post owner. A question can be made community only by moderators, see also the discussion here: Community Wiki in the hands of moderators.

It is probably also worth mentioning that community wiki is (currently) used on MathOverflow slightly differently than in the rest of Stack Exchange network (at least in some cases). Some more details on this can be found, for example, in these discussions:

history | excerpt history