Social networking accounts for one in every four and a half minutes of the world's internet browsing time – some 110 billion minutes per month - according to statistics from Neilsen.
The analytics firm said three quarters of global internet users visit social networking sites.
The number of visitors to such sites has grown nearly 24% in the last year, and the average visitor spends 66% more time on them than they did a year ago.
Facebook is now the third most visited brand of site online, with 54% of the world's internet population visiting it. The average user spends 6 hours per month on the site.
Brazil is by far the most prolific user of social networking sites, with 86% of the population doing so. Nielsen said this is because of the popularity of the Google-owned Orkut site, which is managed by Google Brazil.
Italy is in second place, with a reach of 78% of active users, followed by Spain with 77% and Japan with 75%.
The country which spends the most time on these sites is Australia, with an average of over 7 hours per month. In the US, Italy and the UK, users spent around 6 hours per month.