Confluence was founded on the principle of a Wiki

A Wiki or wiki (pronounced "wicky" or "weekee", see pronunciation section below) is a website (or other hypertext document collection) that allows a user to add content, as on an Internet forum, but also allows that content to be edited by any other user. (http://en.wikipedia.org/wiki/Wiki)

How is Confluence useful?

Confluence lets large groups of users create and edit information together. It includes added functionality which other knowledge management tools do not possess.