I was going through the Badges and stumbled upon 'non-community wiki answers' in the Tag Badges section.
Usual answers are
non-community wiki unless you check a small check-box labelled community wiki under the answer box (bottom right).
Moderators can also convert questions and answers to
community wiki. When a post is made
community wiki then the poster does not get the rep points (both positive and negative) and the reputation requirements for editing are reduced. This basically allows anyone to edit the post so that the post can become a community effort. Community wiki points also do not contribute to your tag-badges but they do contribute to
enlightened, etc badges.
If you are posting some kind of canonical Q/A as some kind of a basic knowledge resource, you can make it a community wiki (for example Why do some bad traits evolve, and good ones don't?).