A wiki post is a post that almost anybody can edit, with the exception of really new users of the forum.
Wiki icon - get a history of changes
Wiki edit button - make an edit
Wiki history
By pressing the wiki icon to the top right of a post, you can get a history of changes.
Making a wiki post
To make a wiki post, first make a post. You can then, assuming required trust do the following.
Reference: Admin settings about wiki posts
