What is Anti Aliasing?

[Guest]

What is AA and when is it useful?
Also what are the different types of AA?
When can it be useful and does it put extra strain on my GPU?

 

[MWP0004]

http://www.howtogeek.com/73704/what-is-anti-aliasing-and-how-does-it-affect-my-photos-and-images/

Here's a relatively detailed article.