Moodle is a course management system (CMS) - a free, Open Source software package designed using sound pedagogical principles, to help educators create effective online learning communities.

You can download and use it on any computer you have handy (including webhosts), yet it can scale from a single-teacher site to a 50,000-student University.

Moodle has a large and diverse user community with over 200,000 registered users on this site alone, speaking over 75 languages in 175 countries (we have more statistics here). The best place to start is Using Moodle, which is where the main international discussions are held in English, but we have a variety of groups discussing other topics and in other languages.

Moodle.org have a long list of developers who contribute towards the development of Moodle. Most discussion can be found in Using Moodle. Moodle is available in a variety of download packages with different levels of stability, as well as via CVS from Sourceforge.net. A number of additional modules/plugins and language packs are also available.