Networks can be use to connect to others for a variety of reasons including:
Professional: LinkedIn think of it as your online resume that keeps building and a way to receive updates from colleagues you don't see on a daily basisEntertainment: Internet Movie Database this site has stopped many debates about who "that guy" in "that movie" we liked last month really was...Relationship: Match they say, "1 on 5 relationships start online"Mutual Interest: Veggie Gardening Tips explore the wealth of information or contribute to the "tip-jar" blogEducational: Educational Networking teachers and students can find common ground in on of these groupsHumanitarian: It's One Humanity inspiring stories that motivate one to action
One social network site can serve more that one purpose...
Online communities have been grown around vendor sites as well. Amazon is a prime example of a seller who encourages customer loyalty and interaction through product ratings and smart referrals based on previous purchases. Although it is an ideal business model for online sellers, it is not a social network because the services are not in place to encourage individuals to develop on-going relationships.