Can someone please explain to me in non-geeky terms what "World of the Wacrafts" is?

The Wikipedia article on it is a total snooze-fest, saturated with ridiculously elaborate acronyms and painstakingly minute details. Can someone just explain to me the gist of the game, without going into any of it's boring technicalities, and give an idea about why it is so appealing to a certain demographic?