DivX is currently the best video compression software available. It can dramatically reduce the size of video files without a loss of quality. That is why it has become popular with people who post video to Usenet. The reason why you have to know about DivX is because Microsoft and Apple do not include it on their computers.
There are many different compression methods, and the software for each one is put into a file called a “codec”. When you try to play a video on your computer, Windows Media Player or Apple QuickTime looks for the appropriate codec to decode the data in the movie file. If the codec is not present, the player can download it automatically. However, so far Microsoft and Apple have refused have their players download the DivX codec.
You can get the DivX codec for Windows and Mac here: www.divx.com. Make sure to download the free codecs. They also have a free movie player called DivX Player which you should keep since it can play some movies that other players cannot. Mac users can also get DivX codecs from 3ivx.
If you have a video file that won’t play, chances are good that you need the DivX codec. However, it is also possible that you need the increasingly popular H.264 codec.
Note: You may have a vague memory of a failed video-disk rental system from the late 1990′s called “Digital Video Express” or Divx. Forget about that; it has no relation to the DivX compression technology.