From Encyclopedia Dramatica
It began as a fork of the Futallaby imageboard software, which was itself a fork of the Futaba imageboard software. It is now completely unrecognizable, having been so heavily modified by moot. Some of the changes were made for security, such as blocking images which contain malware (as well as lots of harmless things). Other changes were made for convenience, such as the floating post box, the thread watcher, the catalog, and a slew of other features which were already available in a plugin used by everyone.