Anonymous is the name generally given to the posters on 4chan, because there's no required log-in, and the default name is 'anonymous'. The whole Guy Fawkes mask deal is simply them having found some icon or another to associate with that they find cool or epic on some level. 4chan is more or less a forum, with various sections for discussion topics, where you can attach images to posts - though don't have to - and threads get purged after being bumped of the board's first fifteen pages.
Most of the time anonymous acts up is either to be dicks or to be good guys, such as when they helped find the woman who threw the puppies in the river, or the guy who threw a dog off a bridge, but other times, when people talk shit on anonymous or make some ludicrous threat, they attack them, such as Jessi Slaughter or the kid who recently 'declared war on Justin Bieber haters'.
stay away from there and don't corrupt it with your newfaggotry
