Moodle is an open source software e-learning platform (also known as a Course Management System (CMS), or Learning Management Systems (LMS), or Virtual Learning Environment (VLE)). It has a significant user base with 25,281 registered sites with 10,405,167 users in 1,023,914 courses (as of May 13, 2007). Amazon.com uses it to train employees.

Moodle is designed to help educators create online courses with opportunities for rich interaction. Its open source license and modular design means that people can develop additional functionality. Development is undertaken by a globally diffused network of commercial and non-commercial users, spearheaded by the Moodle company based in Perth, Western Australia.

Moodle is a software package for producing internet-based courses and web sites. It's an ongoing development project designed to support a social constructionist framework of education.

Moodle is provided freely as Open Source software (under the GNU Public License). Basically this means Moodle is copyrighted, but that you have additional freedoms. You are allowed to copy, use and modify Moodle provided that you agree to: provide the source to others; not modify or remove the original license and copyrights, and apply this same license to any derivative work.

Moodle can be installed on any computer that can run PHP, and can support a SQL type database (for example MySQL). It can be run on Windows and Mac operating systems and many flavors of linux (for example Red Hat or Debian GNU). There are many knowledgable Moodle Partners to assist you, even host your Moodle site.
The word Moodle was originally an acronym for Modular Object-Oriented Dynamic Learning Environment, which is mostly useful to programmers and education theorists. It's also a verb that describes the process of lazily meandering through something, doing things as it occurs to you to do them, an enjoyable tinkering that often leads to insight and creativity. As such it applies both to the way Moodle was developed, and to the way a student or teacher might approach studying or teaching an online course. Anyone who uses Moodle is a Moodler.

Moodle features
Moodle has many features expected from an e-learning platform including:

1. Forums
2. Content managing (resources)
3. Quizzes with different kinds of questions
4. Blogs
5. Wikis
6. Database activities
7. Surveys
8. Chat
9. Glossaries
10. Peer assessment
11. Multi-language support (over 60 languages are supported for the interface)

Moodle is modular in construction and can readily be extended by creating plugins for specific new functionality. Moodle's infrastructure supports many types of plugin:

1. Activities
2. Resource types
3. Question types
4. Data field types (for the database activity)
5. Graphical themes
6. Authentication methods
7. Enrollment methods
8. Content Filters
9. Many third-party Moodle plugins are freely available making use of this infrastructure.

PHP can be used to author and contribute new modules. Moodle's development has been assisted by the work of open source programmers. This has contributed towards its rapid development and rapid bug fixes.