Drupal is an open-source platform and content management system for building dynamic web sites offering a broad range of features and services including user administration, publishing workflow, discussion capabilities, news aggregation, metadata functionalities using controlled vocabularies and XML publishing for content sharing purposes. Equipped with a powerful blend of features and configurability, Drupal can support a diverse range of web projects ranging from personal weblogs to large community-driven sites. Due to its modular design Drupal is flexible and easy to adapt or extend. The Drupal platform, written in PHP and utilizing a database back end (e.g. MySQL or PostgreSQL database) provides APIs that facilitate the development of building blocks (modules) that seamlessly integrate with each other. The functionality of Drupal systems can be easily extended by adding and configuring new modules. The source code is available under the terms of the GNU General Public License (GPL).