Troll
Trolls are typically thought of as scary creatures that live underneath bridges. While these mythical creatures may only exist in legend, "Internet trolls" are real and cause real problems. In computing, the term "troll" refers to a person who posts offensive, incendiary, or off topic comments online. These comments may appear in Web forums, on Facebook walls, after news articles or blog entries, or in online chat rooms.
Trolls post off-color comments for a number or reasons. They may want to stir up an argument or may simply want attention. Some trolls use comment sections after news articles to rant about their feelings, which may or may not be related to the news story. Whatever the case, trolls are seen as a nuisance in online discussions. At the least, their comments distract from an otherwise legitimate discourse. In worse cases, trolls stir up emotions from other visitors, creating unnecessary arguments.
The action of posting obscene or inflammatory comments is often called "trolling." This activity is highly discouraged and may actually a violation of online community's user agreement. Fortunately, webmasters and forum moderators typically have the power to remove offensive or off topic posts and even terminate accounts if needed. While we enjoy the liberty of free speech online, it is still important to respect others. Therefore, remember to show common courtesy when posting comments online and don't be a troll!