Moodle is an open source VLE written in PHP, and utilising an SQL database for storage. Both MySQL and PostgreSQL work well with it. It is currently enjoying success across the educational spectrum because it is simple to install, is easy to use, is flexible, powerful and extensible.
Moodle has a service-oriented business model. "Authorised Moodle Partners" provide customisation, support, software development, integration services, installation, consultancy, training and hosting in various countries and regions and pay The Moodle Trust a portion of their income. The Moodle Trust uses the money to keep moodle.org and moodle.com running and connected to the net and to pay for key developers, currently mainly Martin Dougiamas, who originally wrote Moodle.
Partners benefit by being able to use the brand in advertising (the name "Moodle" is a trademark), users benefit by being able to easily identify specialist developers in good standing in the Moodle community and Martin Dougiamas benefits by having an income stream to maintain and develop the software.
OSS Watch supports Moodle use in the UK by helping make Moodle Moots happen. Moodle Moots are gatherings of teaching staff, techies and other moodle-heads to network, review developments and plan the future. Planning for the next Moodle Moot in the Summer of 2006 is underway.
OSS Watch also produces a Knoppix (live Linux CD) customisation which includes a running Moodle system, which gives you a chance to try Moodle easily; the Moodle site itself also uses Moodle, so that is a good demonstration.
Are you using Moodle? Edit this page to tell us about your experiences.