Example: "I wish trolls would stop posting off-topic comments in this thread."
In Internet terminology, a troll is a person who posts offensive or off-topic comments online. These comments are often made to incite arguments or emotional responses from other users. Trolling, as it is called, may take place in Web forums, in blog comment sections, and in social networking websites.
Usernames provide trolls with hidden identities, and therefore a sense of anonymity online. Therefore, trolls often type things they would not actually say in person. The anonymous nature of the Internet gives trolls the capacity to post offensive comments without being held responsible. Fortunately, webmasters can typically delete unwanted posts and remove the accounts of the trolls that invade Web forums and other online communities.
Updated: May 2, 2011