How Online Social Networks Work

Whil­e adults have joined online social networks that have been previously dominated by teens like MySpace and Facebook, adult users are also joining online social networks targeted at adult members. Adult social networks don't specialize in "adult" content (although those certainly exist), instead they're social networks for professionals rather than purely for friends.

With over 15 million members, LinkedIn is the largest online social network for business professionals. On LinkedIn, profile pages read more like resumes, citing professional experience and education and leaving out personal tidbits like favorite books and bands. Not until recently did LinkedIn even allow users to post a profile picture for fear that it would turn the strictly business site into yet another excuse for online dating.

LinkedIn users can leverage existing contacts and relationships to find new jobs and partnerships. On LinkedIn, for example, you can search for job postings within your network. If it turns out that your best friend went to college with the guy who's hiring, that could give you a significant advantage over other applicants.

Professional recruiters are also tapping into the tremendous professional databases on sites like LinkedIn. Recruiters can pay extra for LinkedIn Corporate Services, a service that allows them to run targeted searches for members who meet their experience and location criteria. The advantage of a service like LinkedIn is that recruiters can zero in on "passive applicants," professionals who are highly qualified but not necessarily looking for a new job. These people are considered more attractive to employers since they've proven their ability enough to hold down a job.

Several adult social networks cater to specific professions. According to an article in the Wall Street Journal, doctors are meeting up on a physician's social networking site called Sermo and advertising, marketing and media execs are sharing tips and tricks on another social network called AdGabber [source: Wall Street Journal].

On the next page, we'll talk about social networks for sneaker enthusiasts.