WIKI Is a web application that allows collaborative editing of its content and structure by its users. Wiki is different from a blog since wiki allows users to add, edit or delete content that is posted on the website while blog does not allow others to modify the original material posted.
The important part of wikis—what makes them different from any other type of website— is collaborative editing by the users. Think about that for a moment: the ability for the users of a wiki to collaboratively edit it. If you can read it, you can edit it. It seems simple at first, yet profoundly powerful in practice—and it's what both Wikipedia and WikiLeaks have in common.
What are its uses?
Wikis can be used to organize all your stuff. You can use wiki to: • promote collaboration among individuals • use as online presentation tool • post announcements, meetings, agenda or discussion • create a to-do-list • organize projects, from planning to implementation • plan an event • enhance teaching and learning • share materials like documents, and other media