pewinternet:

Our latest report takes a quick but informative look at why Americans use social media:

Two-thirds of online adults (66%) use social media platforms such as Facebook, Twitter, MySpace or LinkedIn. These internet users say that connections with family members and friends (both new and old) are a primary consideration in their adoption of social media tools. Roughly two thirds of social media users say that staying in touch with current friends and family members is a major reason they use these sites, while half say that connecting with old friends they’ve lost touch with is a major reason behind their use of these technologies.

Other factors play a much smaller role—14% of users say that connecting around a shared hobby or interest is a major reason they use social media, and 9% say that making new friends is equally important. Reading comments by public figures and finding potential romantic partners are cited as major factors by just 5% and 3% of social media users, respectively.