Berlin is a windowing system derived from Fresco, a powerful structured graphics toolkit originally based on InterViews. Berlin extends Fresco to the status of a full windowing system, in command of the video hardware (via GGI, SDL, DirectFB or GLUT) and processing user input directly rather than peering with a host windowing system. Additionally, Berlin's extensions include a rich drawing interface with multiple backends, an upgrade to modern CORBA standards, a new Unicode-capable text system, dynamic module loading, and many communication abstractions for connecting other processes to the server. It is developed entirely by volunteers on the internet, using free software, and released under the GNU Library General Public License (GPL).