Open Source
The basic idea behind open source is very simple: When programmers can read, redistribute, and modify the source code for a piece of software, the software evolves. People improve it, people adapt it, people fix bugs. And this can happen at a speed that, if one is used to the slow pace of conventional software development, seems astonishing.
Moodle is a Course Management System - 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, yet it can scale from a single-teacher site to a 50,000-student University. Moodle has a large and diverse user community with 130,000 registered users. The software is offered in over 70 languages resulting in its use in 214 countries.