Scroll over the i bubbles to see country specific information.
Credit: Alastair Halliday

*Site rankings are based on data from the Web information service Alexa and were vetted by Danah Boyd, a fellow at the Berkman Center for Internet and Society at Harvard Law School. This list reflects only those sites devoted specifically to displaying social networks, sites Boyd calls "social-network sites." According to Boyd, two other such sites--Windows Live Spaces and the Chinese site QQ--might rank in the top five, but available data are incomplete.

Since the first websites devoted to displaying social networks launched in the late 1990s, millions of people have connected with friends through services like MySpace, Hi5, and Cyworld. Recently, the greatest growth in the sites' popularity has occurred outside the U.S. In Asia and Australia, for example, the number of monthly users of social-networking sites (under a broad definition that includes, for example, blogging sites) jumped nearly 50 percent, to 169 million, in 10 months. Some sites have capitalized better than others: San Francisco-based Hi5, which translates pages into Spanish and Portuguese, is now the world's third-largest. A shakeout is ­inevitable in 2008 as patrons of many sites choose favorites.