While I have never personally been to an anime convention, I do know several people who have. There are many different types, from general ones to very select ones, though most are very general. In addition, while they don't really qualify as anime conventions like you'd think of, video game conventions do have a lot of cosplay involved like most anime conventions do. For those of you who aren't familiar with cosplay, it's very simple. Pick a character from an anime, game, movie, etc. (make sure you're not dressing up as an anime character for a Star Wars convention or anything else! In other words, make sure that the character you pick is in the genre for the convention you're going to!) and either buy or make a costume (hence the term cosplay) for you to wear to the convention.
The goal is to appear as much like that person as possible. I've seen pictures that my friends have brought back from conventions of cosplayers and while some of the costumes are fantastic (looking at least 95% like the person they're dressing up as), a lot of them are total let-downs as well. I remember seeing one person that had the outfit right, but the hair color all wrong! Also, at conventions such as these, there are usually lots of events to participate in and lots of things to buy. From everything I've heard, conventions are a LOT of fun and I plan on attending one in the near future!
