Moodle is an open source software package that is used to create Internet-based learning materials and courses. Moodle is provided freely under the open source GNU Public License. This means that Moodle is copyrighted, but the users have the right to copy, use, and modify the source code provided that they agree to provide the modified source to others, do not remove or modify the original license and copyrights, and apply the same license to any derivative work. This, in layman's terms, means that you can do what you like to Moodle as long as you ensure that you do not attempt to copyright any of the modifications that you might introduce.

Moodle was originally an acronym for Modular Oriented Dynamic Learning Environment, which of course is mouthful and not very useful unless you are an educational theorist. At the time of writing, Moodle has a significant user base of some 43,000 registered sites in 208 countries, and is continuing to grow at a significant rate.

Moodle can be installed and run on any web server software that uses Hypertext Preprocessor (PHP), and can support a SQL database. MySQL is the database of choice, but Moodle can nevertheless be run on MS SQL, Oracle, and most other types of SQL databases.

Moodle can be run on the Windows and Apple Mac operating systems, and can also be installed on many different Linux distributions, including Red Hat, Ubuntu, and CentOS.

Moodle has many features that are expected from most e-learning platforms, and also has some of its own innovative features that set it aside. Moodle is a modular platform and therefore can be built to order, and can be readily extended through the use of third-party modules and extensions.