Everyone knows what a social network is. It's your family, friends, and neighbors. It's your co-workers, customers, and business contacts. It's the fabric of your community and the common threads that connect you to the people in it. But in our increasingly web-centric world, the terms “social network” and “social networking” have taken on another shade of meaning. Nowadays, when someone says “social network,” chances are they're referring to a relatively new generation of online communities, such as Facebook, MySpace, and LinkedIn.