1) Socialise with people who have similar tastes
or 2) Allow them to stalk the girl next door
Some examples of these sites include MySpace, Facebook and Bebo, each of which attract their own clique of people.
MySpace attracts musicians, emos, and stalkers
Bebo attracts children pretending to be adults, Irish college students, and stalkers
Facebook attracts people who have nothing better to do with their time, namely stalkers
Tom Anderson: MySpace!
Mark Zuckerberg: Facebook!
Michael Birch: Bebo!
Random Internet Guy: Insert Social Networking Site Here!
Guy 2: Yeah right, social networking is the gayest thing to happen to Earth since reality tv.
(v.) When a person prefers to talk to their "friends" online instead of in person. Generally used by nerds who enjoy insulting others and not having the balls to insult them to their face. When this is used, that person is generally anonymous, due to the risk of being seen in public (which they really don't have to worry about, because they're always sitting in front of a computer). Social networking is also used by stalkers, due to the ability to appear as someone you are not. This tactic is also used by people who love hearing "omg ur soo hot lolol" and use a google picture, saying it is them.