All this bollox about DivX - is it simply an AVI video file? Or does it have to be specially encoded?

When you download a file, a lot of the time it says "name of film/DVDRip/DivX.AVI" and is a normal AVI file....

So if this is what DivX is, how do you burn it to CD and watch it on a DivX-compatible DVD player.... If I use Nero and burn as "Video CD" it converts it to shit quaity VCD format....

So do I just burn it as a data disc or something?