AVI Files
Explained in Plain English

AVI is Mircrosft's video format. AVI is popular becuase it can take advantage of newer, and better compression schemes as they are developed. The data inside an AVI file can be compressed in many different ways. This is possible because AVI is designed to work with software called "codecs." A codec decodes the compressed data into a movie. So, for example, if you have an AVI movie that was compressed with DIVX, Windows Media Player will use the DIVX codec to decompress the movie as it plays.

AVI's flexability is also a drawback because if you download an AVI file, you often can't tell in advance if you will be able to play it. You may have to spend time hunting down and instaling the proper codec.

QuickTime can play AVI's on the Macintosh, but you still need the proper codecs. Mac users should keep in mind that the people who create AVI's do so on Windows computers, and that sometimes the movies won't play properly on the Mac.