OpenACS (Open Architecture Community System) is a web application platform designed for high traffic community websites. It is built on a free and open source foundation. OpenACS is the foundation for many products and websites including the .LRN e-learning platform (www.dotlrn.org). OpenACS runs on AOLserver and uses either the PostgreSQL or Oracle (which is not open-source) relational databases. It uses TCL as its main language. AOLserver, postgresql and Oracle are used in some of the most demanding, high-traffic web applications in the world. DotLRN (.LRN) is built upon openACS core, but includes extra modules and configurations. DotLRN has its own tarball and port (openacs-dotlrn). WWW: http://openacs.org