Social networks can be a great way to meet people and connect with friends and coworkers. Based on Stanley Milgrim's six degrees of separation finding, social networks allow you to establish contact between overlapping circles of acquaintance. Columbia University proved in 1998 that Milgrim's networking model holds up online as well, although only when participants are motivated (for example, when they believe there's a good probability of success).
In the online world, features and functionality help to ensure that belief. Detailed profiles, recommendations, and photos help create a feeling of intimacy, so it is easier to reach out to people you don't know.
Friendster, the de facto standard in online social networks, has the largest community so far, although you won't necessarily see this because you see only the people who are in your circle of acquaintanceup to three degrees out. If you're looking for a date or a play date for yourself, it's a good place to hang out.
Orkut is also a good place to hang out with your acquaintances, be they friends or friendly co-workers. With a rich set of tools, including messaging, rating, and the ability to create communities, Orkut offers a wired way to connect with distant friends.
For something completely different, LinkedIn is a social network aimed at solving business problems. When you need skilled labor or a contact at a specific company, you can cold call, but why do it the hard way? LinkedIn lets you tap your professional network to leverage recommendations from people you know.
These social networks are still in a beta period, which means they are free services, although they all make it clear that that is a limited-time offer. Two of the services, Friendster and Orkut, also demonstrated some page time-out problems, which was annoying, but didn't result in any data loss.
Online social networks give us a way to get to know the people who know the people we know, in way that's browsable and searchable. Although that may also help us solve an immediate problem we have, it allows us to deepen our existing friendships.