In Internet slang, a troll is someone who posts inflammatory,[2] extraneous, or off-topic messages in an online community, such as an online discussion forum, chat room, or blog, with the primary intent of provoking readers into an emotional response[3] or of otherwise disrupting normal on-topic discussion.[4] The noun troll may refer to the provocative message itself, as in: "That was an excellent troll you posted".
"Do not feed the trolls" and its abbreviation "DNFTT"
From Wikipedia.
