Moodle is a course management system (CMS) - a free Open Source
software package designed to help educators create effective online
courses based on sound pedagogical principles. 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 200,000-student University.
Moodle has a large and diverse user community with over 50,000
installations worldwide speaking 75 languages in 200 countries.