At first glance, it would seem reasonable that, because internet users are anonymous (or at least as anonymous as they choose to be), racism and sexism would be practically nonexistant on the internet. In fact, I’ve heard several people refer to online environments such as message boards, chatrooms, and computer games as near-perfect meritocracies.
In reality, this is not the case. First, racism and sexism are not unknown on the internet. The KKK can set up a website just as easily as anyone else, and racist or sexist attitudes may simply be less visible on message boards because users are not aware of other users’ race or gender. For a mildly amusing account of the “Boys Only” attitude of many gamers, see this article by Whitney Butts.
Even without the old standby segregators like race and gender, there’s no reason to assume that other factors won’t simply take their place. Almost any community of decent size will have smaller cliques of people who can be more or less hostile to other cliques. In a basic form, one can be judged online based on username, avatar image, signature, spelling and grammar, and, of course, the ever-popular religious or political views. If you’re ever bored, go to a discussion board with a definite political bias (say, the neoconservative Free Republic), and post something diametrical to the majority opinion to see how long it takes to get banned. For an amusing discussion of Free Republic’s forum, see this board at ALIPAC’s (anti-illegal immigration group) forum.