Drupal is written in PHP, a programming language known for its usefulness in producing dynamic web sites. Drupal works with Windows, Mac OS X, Linux and many other operating systems. However, it does require a database, such as MySQL to store content and settings. Anyone can create modules for Drupal, and currently available modules range from photo galleries to e-commerce systems. Modules can even change Drupal\'s default behavior in order to build a better website.