Basically trolls are jerks who go about starting crap on message boards by flame baiting, insulting others, and posting things they know will offend the community. (I. E., posting about their new catskin rug on a cat lovers forum.)
"In Internet slang, a troll ( /ˈtroʊl/, /ˈtrɒl/) is someone who posts inflammatory,[1] extraneous, or off-topic messages in an online community, such as a forum, chat room, or blog, with the primary intent of provoking readers into an emotional response[2] or of otherwise disrupting normal on-topic discussion.[3] The noun troll may refer to the provocative message itself, as in: "That was an excellent troll you posted.""
http://en.wikipedia.org/wiki/Troll_(Internet)
We have at least one person who we suspect of using different user names to proclaim how it's okay to use people and fake marriages to enter Canada. He's a troll in addition to encouraging criminal behavior.
However, by the definition (posts.... extraneous, or off-topic messages) I am DEFINITELY a troll!!!!! But the fun kind.