MediaWiki is a free wiki software package that can be used to install Wikipedia like collaboration environment on any website or server. If you’re looking for a flexible wiki Content Management System then MediaWiki is the package you need. It can be used for a wide variety of projects, regardless of the amount of people involved.
Whether it’s a solo writer writing a book or a 100 people team working on a massive assignment, MediaWiki can handle it. It’s simple to install, very easy to learn, and absolutely free.

Some Features
- Collaborate with as many people as you want.
- Extendable: Install extensions for additional functionalities (add calendar, integrate chat, add backup /restore functionalities, clipboard, etc.). Hundreds of extensions available.
- Fullly configurable: change look and skin, restrict certain pages, add categories, enable / disable file uploading, and lots more.
- Support: Well documented. So if you want to add something to your wiki but have no clue how it can be done just search for it on MediaWiki.org
- Note: Several webhosts include a preconfigured MediaWiki with the hosting package. Contact your host for details.
Used by over 50 popular online websites (incl. Wikipedia). Check out the full list here.
[Video] Wikis in Plain English
Get MediaWiki @ www.mediawiki.org