TeknologikL

AVI should be dead and gone by now, but it is still the most widely circulated video container. AVI, which stands for Audio Video Interleave, was developed by Microsoft and released all the way back in November 1992 - ancient history as far as video standards go.

Native Support
Giving AVI a boost is the fact that support for the container is built into Windows. But, even with native support for AVI in Windows, many users run into issues playing certain files - often getting sound but no picture. This is a result of the video codec used within the AVI container not being supported by your media player.

By installing a codec pack that has most of the popular codecs included, you will alleviate many of these problems.

Uncompressed AVI
Although most AVI files are compressed with a video codec, AVI files can be left uncompressed. Leaving them this way will result in an extremely large file size, but without quality loss and it requires no codecs for playback.

DivX
The DivX codec has become one of the most popular codecs (along with XVid) used for compressing AVI videos due to the relatively small file size and low quality loss after decoding.

DivX released its own video container aptly named DivX Media Format (DMF) with a .divx file extension. This new format was an extension of the AVI file container with additional features and isn't widely used.

Nothing to Stream Here
You have probably heard of the term "streaming video" where the user watches a video as it is being downloaded from the internet; well, the Audio Video Interleave container won't help you with that. Due to the file structure of AVI files, media players require the entire file before it can begin playback.

B-Frames
One of the major drawbacks of the AVI container is that it has no support for B-frames. B-frame is short for bi-directional frame or bi-directional predictive frame. This is a technique used in current compression methods that takes data from the frames before and after the B-frame to predict what the B-frame will look like. This gives the ability to store only the information that has changed from the frame preceding and following the B-frame, making for a smaller file size.

Although newer formats offer more advanced features and better compression methods, AVI has been able to weather the storm thus far - mainly due to widespread software support and hundreds of millions of AVI files already in circulation.

Does the AVI format still have a place in your heart or are you ready to move on?

More Info:
Afterdawn: AVI
Wikipedia: Audio Video Interleave
Practical Disadvantages of AVI