blished around special interests such as music or particular sports. One specialized social network, LinkedIn, is designed for business people. Profes- sionals use it to network with others in their field. It is international in scope with more than half of its members based outside of the United States. LinkedIn was established in 2003, earlier than Facebook, which was started in 2004. LinkedIn is a forum for people to offer services such as training in new technologies and discuss issues perti- nent to particular fields. It is not unusual for posts offering services based on new tech- nologies to attract hundreds of responses. In addition, recruiters post job openings and people explore employment opportunities by using these posts, which are organized by specific careers. Social networks are adding applications such as games to boost revenue. There are currently 1,500 online games in a dedicated section for social games on Facebook. These include Farm Ville, FrontierVille, and Texas HoldEm Poker from Zynga. Other The Internet companies such as RockYou develop games created specifically for social networks. In these games, people compete with other participants by adding to their frontier area or farm. In FarmVille, participants pay for virtual goods, including farm equipment and crops, to expand their farm. Game developers share a portion of their revenue with the social network. Twitter is another form of social networking. People use Twitter to broadcast microblogs, or "tweets," of not more than 140 characters to others who "follow" them. Many celebrities and most businesses have a presence on Twitter. They use it to post timely information about their business and for public relations purposes. Interest- ingly, Twitter is used more by people older than 25 than by teens who rely more on texting on mobile devices, which is more private and not as easily seen by adults. Commercial organizations use both Facebook and Twitter to promote their prod- ucts and to monitor people's reactions to their products and ser