I Don't Know Much, But What I Do Is Geeky

Seriously, I really don't know much beyond the "nerds in a comic book shop pretending to be characters similar to those in Middle Earth and taking a game more seriously that most other people would" stereotype. I know there are dice. I know that you CAN dress up, but you don't HAVE to. I thiiiink there are a lot of rules ad people can get pretty heated about various versions of the rules? I connect it with WoW and other video gamey type people, but I imagine that's not the whole story.