The social network, smaller: Facebook to blame?

The Internet has become a voracious social animal, and Facebook is to blame.

The giant social network taught us to go online and share all kinds of previously personal information with strangers. Now, scores of smaller websites are taking a slice of Facebook’s action, creating communities for people with specific interests, from shared medical conditions to avoiding the next highway speed trap.

Pinterest is a combination bulletin board and search engine, where users can share hobbies ranging from old cars to architecture. Trapster is a community of drivers who swap sightings of police radar setups. Ravelry, a group of knitters, is one of numerous social networks built around a hobby. On PatientsLikeMe, people with similar medical conditions can swap their experiences and symptoms.

‘’Humans are social creatures,’’ said Amanda Lenhart, senior research specialist at the Pew Research Center in Washington, D.C. ‘’These sites are all about allowing you to be seamlessly social, and that’s very compelling.’’

What was once solitary in real life is increasingly social online. Last year, 65 percent of adults on the Web said they used social media sites, more than double the amount in 2008, according to the Pew. But where Facebook grew by connecting friends and family, the next wave of social media will be built around shared personal interests, said Andrew Lipsman, vice president of industry analysis for comScore Inc., a firm that measures Web traffic.

Sharing interests drove the phenomenal growth of Pinterest , a social media site that allows users to clip pictures and text on such eclectic subjects as home decor, recipes, and vintage cameras, on a virtual pinboard for other fans to enjoy. The site, based in Palo Alto, Calif., grew from 400,000 visitors last May to 11 million last month, according to comScore. ‘’That’s the fastest 10 million that we’ve ever seen,’’ said Lipsman.

Pinterest did not return requests for comment, but its stated mission is ‘’to connect everyone in the world through the ‘things’ they find interesting.’’ It exemplifies how narrow-interest social media sites ‘’have the potential to consume a significant amount of users attention, engagement, and ultimately ad dollars,’’ said Lipsman.

Trapster, based in Carlsbad, Calif., and owned by the Finnish phone maker Nokia Corp., is not built on the shared interests of hobbyists, but of drivers - especially those who want to avoid speed traps. Through its smartphone app, users can post and read where accidents have caused traffic jams, or where to slow down to avoid police. ‘’People have been flashing their headlights, warning other drivers, for a long time,’’ said Sean Farrell, product manager for Trapster, which has been downloaded on 15 million devices worldwide. ‘’This just moves it into the digital age.’’

He denied that Trapster encourages scofflaws. ‘’We are not saying, ‘Download Trapster and drive like a maniac,’’’ he said.

Sites such as Trapster and Pinterest may not ever grow as large as Facebook, which has 845 million users worldwide and intends to go public in the spring. In fact, some social media start-ups count on Facebook’s sheer scale, using the giant network as a platform rather than building networks of their own.