Numbers from Compete.com show that although Facebook has taken the lead over MySpace in monthly unique visitors with 1.2 billion, the big winner in the social networking area is Twitter which jumped from the 22 nd most visited site in 2008 to the third most visited social networking site in January 2009, a growth of 1, 227 per cent in 12 months.

One of the key metrics measured by Compete.com revolves around the activity of the user base, visits per unique visitor and time on site. Based on that, here are the 25 most visited social networking sites: