Drupal is an open source Content Management System, developed in PHP and published under GNU/GPL, with a good and clean design, powerful and flexible. This is my CMS of choice, after testing a number of them and comparing usability, performance and code. I am a Drupal core developer and an active member of the Drupal community, the author of modules like Internationalization. Being an active member of the Drupal community for some years now, I've participated in a lot of Drupal events and conferences on which I am a regular presenter. Currently I am working on multilingual Drupal and the related D8MI core initiative.