This document discusses social networking sites and their use for business purposes. It begins with definitions of social networking sites and a history of major sites like SixDegrees, Friendster, MySpace, and Facebook. Advantages of using social networking sites for business include low-cost publicity, direct access to customers worldwide, and effective marketing. Challenges include privacy issues and lack of anonymity. The document concludes that social networking sites are an important marketing tool for businesses to connect with customers.