What Is A Troll?The term derives from "trolling", a style of fishing which involves trailing bait through a likely spot hoping for a bite. The troll posts a message, often in response to an honest question, that is intended to upset, disrupt or simply insult the group.
Usually, it will fail, as the troll rarely bothers to match the tone or style of the group, and usually its ignorance shows.
The site:
http://www.flayme.com/troll/All about spammers and trolls.