What Are They?

What are the animations that move, change colors, morph, flash like a neon sign, etc., and can be found on web pages and that are sometimes used in forums as "Avitars"(?), or moving pictures in an e-mail. I know there are some free e-mail add ons you can get on the net for free that will allow you to put moving Icons into an e-mail, but from what I've seen of these programs, they all seem to be loaded with spywear. I'm looking for something much broader in scope and not so nosy. Is this stuff some sort of HTML? Is there a program I can buy or a method I can learn to create these animations? Owned a computer now for three and a half years, finally got around to asking this question. Thanks for any info!-Signed, Wondering.

Thanks, kinetic! Found at least one tutorial on the net so far on how to create them. Just got to wondering. Thanks!