DivX is seen as the video equivalent of MP3. You compress video and audio into a format known as MPEG4, which then become small sized movie files (about one-tenth of the size) than those you would see as an MPEG2 or DVD file. In the same way as MP3, the quality does not suffer making it an ideal format for portable DVD players or internet based Pay per view material.

This high level of compression also means that video footage can be downloaded across the internet using peer to peer programs such as Kazaa, eMule, Bittorrant and Limewire.

In order to play DivX encoded video footage and films, you needed to download software from DivXNetworks Inc who are the company behind the format, and you would be limited to watching these movies on your PC. At the end of 2003, several set-top DVD players started to include DivX compatibility and more recently pocket PCs (such as the Joycoder) have also been made capable of handling the file format.

What are the different flavours of DivX? And what is XviD?
You'll see references to various versions (also known as "codecs") of DivX, such as 3.11, 4.xx and 5.xx dotted around articles to do with DivX. Here's a brief summary of each of the versions :

DivX 3.11

Microsoft were responsible for the introduction of MPEG4 compression, however their version was limited to converting their own proprietary video file formats, such as .asf or .wmv. Thankfully, invented a way to enable .avi files that are generally associated with Real Player, to be compressed also.

DivX 4.xx

This was source code that was developed from scratch by DivX Networks, thus removing the need for Microsoft software all together. This has been completely superceded by...

DivX 5.xx/DivX 5.xx Pro

These are the most recent codecs of the format, again created by DivX Networks. The "Pro" version adds significant extras, such as a faster encoder, but the free version installs some spyware on your PC which can only be removed if you have the paid-for version. DivX 5.xx is backward-compatible with the two previous codecs.

XviD

Not actually DivX, it is another format of MPEG4 compression which is becoming increasingly popular as XviD is pure open source coding.

The future of DivX ?
We are still in the early stages of DVD hardware compatibility and they are still ironing out some glitches such as support for subtitles, however with DivX compatibility crossing over to mainstream DVD hardware, the future looks very bright for the format as a viable home entertainment medium in years to come. With pay-per-view titles already available and the continuing convergence of computer and home entertainment technology, it seems that this micro-sized video format is set to become as popular as .mp3 in the family home.