How many friends are you stashing away on Facebook? A few hundred? A few thousand?
How many of those 'connected' people would you actually depend on in moment of emotional crisis? Does your online pool of mates supply you with more "true friendships" than the offline world ever could?
That's the question that Robin Dunbar, professor of evolutionary psychology at Oxford University, set out to answer with his recent study of social media.
Dunbar looked at a sample of 3,375 Facebook users aged between 18 and 65. The average number of friends was 150, but when asked how many of those were "genuine" friends, the answer dropped to an average of around 27.6 percent.
As to how many of those friends they would be able to rely on when personal crap hit the figurative fan, the number dwindled even further - to an average of 4.1. Some 13.6 friends would express sympathy.
"Analyses of traffic in online environments such as Facebook and Twitter reproduce rather faithfully both the nested structure of the inner layers of offline networks and their typical interaction frequencies," writes Dunbar - which, in plain English, means that online tools such as Facebook and Twitter haven't caused all of us to suddenly gain more "real" friends than before the days of the web.
But I've got over a thousand friends on Facebook - and I'm definitely close to more than four of them, you may well think. According to Dunbar, you might just be more flexible in your understanding of "friend".
"Respondents who had unusually large networks did not increase the numbers of close friendships they had, but rather added more loosely defined acquaintances into their friendship circle simply because most social media sites do not allow one to differentiate between these layers."
So, don't start thinking that you've got an army of faithful buddies based on your Facebook or Twitter count. Friendship hasn't changed in the digital age.