Internet socializing has become hugely popular, and Web sites that help people meet potential dates, find new friends and keep track of old ones are big business. Hundreds of sites attract tens of millions of users, and more sites come online daily. Born along with the Internet in the early 1970s, online socializing has helped people worldwide link to others with common interests for conversation and support. Nevertheless, new social-networking sites like Facebook and MySpace raise more troubling privacy issues than traditional Internet chat rooms. Visitors to such sites can access not only individuals' posted profiles but also profiles of their friends. Parents and law-enforcement agencies worry that predators can use the information to contact vulnerable teens. Some states are considering requiring tighter security and confidentiality, and a bill introduced in the House of Representatives would require schools and libraries to block teenagers from the sites.