A troll is basically one who posts messages intended to insult and provoke per fas et nefas
For each person who responds, the poster (the troll as a person) will consider that person "caught". The troll (the troll as an action) is considered to have been a complete success if it disrupts beyond repair the normal traffic on a newsgroup or on a messageboard.
In extreme cases, trolls are posted by groups of trollers and crossposted to unrelated newsgroups in an attempt to destroy those groups by flooding them with flames and off-topic ranting.
Thirty - Eight Ways to Win an Argument
from Schopenhauer's "The Art of Controversy"