XviD is an open source MPEG-4 video codec designed for everyone. Its purpose is to compress video in order to allow for faster transmission over computer networks or for more efficient storage on computer disks. Hence, XviD can somewhat be seen as a ZIP archive for video. XviD removes information from video that is not important for human perception in order to achieve very high compression rates while still keeping very good visual quality. XviD is published under the GNU GPL license. That means it can be obtained free of charge. And since XviD is open-source software, everyone can review the XviD source code to check for himself that nothing malicious is included.