Wiki

A wiki is a web application that allows users to add content, as on an Internet forum, but also allows anyone to edit the content. "Wiki" also refers to the software used in such websites. For a more complete definition, see WikiPedia:wiki.

The wiki format is particularly useful in a community setting, where it can be used as a repository of collective wisdom and knowledge, refined and developed by an iterative collaboration process, as well as serving as a central reference point for various community activities (IRC channels, real-life get-togethers, etc.)