What is Adobe After Effects?

I have question, about Adobe Effects. What is Adobe Effects used for, per say in a vid? I know some vidders use it, I know in part it's to create motion graphics(am I wrong)? Apologies if this has been asked before.

[identity profile] used2bvader.livejournal.com 2006-04-13 08:52 pm (UTC)(link)
If you watch my latest video of "the Internet is for porn" there are 2 shot there that I couldn't have done without After effects both are Obi wan looking at screens, one is a still image put into the video, the other is video of Oola dancing from Return of the Jedi on his screen.

[identity profile] used2bvader.livejournal.com 2006-04-13 08:53 pm (UTC)(link)
oops here's the video

Warning: the following Video deals with words and
Ideas unsuitable for Children under 15. Parental
guidance is suggested.


http://rapidshare.de/files/17883295/Internet4porn.wmv.html

YSI
http://download.yousendit.com/5C2F83A7356513A8