Veganism is a diet that obstains from any animal products (meat) or bi-products (i.e. eggs, milk, wool, leather, etc).
Most people will assume that because you follow a vegan lifestyle, you must be a pretentious jerk (or in a cult). This is NOT always the case (although you do have your exceptions that give the rest of us a bad name).
Being vegan doesn't mean you have to be a part of any organization (i.e. PETA) or chain yourself up and protest. It just means that you choose to follow a 100% herbivore diet for whatever reason. Choosing to be vegan for diet purposes or animal rights purposes doesn't matter, as long as you're doing it because YOU want to.
If you do it correctly you DO NOT GET SICK and you DO NOT NEED SUPPLIMENTS in order to be healthy and happy. :-.)
*At a "mixed" bbq party* (Who would have thought vegans dine with meat-eaters? Yes, it's true, we do! OMG!)
John: Would you like to try some teriyaki steak tips?
Jane: No, thanks, I'm vegan. I would love it if you could pass me the tofu fritters though.
John: No, problem. *passes fritters*
THE WORLD CONITNUES UNINTERRUPTED AND NOBODY NEEDS TO STAND ON A SOAP BOX AND BELITTLE EACH OTHER. AWESOME.