Moodle is a free open-source learning management system originally created by Martin Dougiamas in 2002. It has over 45,000 registered sites used by over 20 million users worldwide. Moodle is designed to support social constructionist learning and allows students to learn from each other and their teacher. While the software itself is free, companies provide support, customization, and hosting services. Moodle's flexibility, large user community, and emphasis on education have helped it grow beyond its origins as a small open source project.