A wiki is a collaborative website which can be directly edited by anyone with access to it. Ward Cunningham, developer of the first wiki WikiWikiWeb, originally described it as "the simplest online database that could possibly work".Wikipedia is one of the best-known wikis. My Freind Lee Leefever made a cool video :

You are using one! So no introduction of Wiki is required! 

How To Use Wikis For Business

How to Use Wikis in the Enterprise: A Primer

Collaborating through wikis