FACEBOOK, whose users visit for an average of 50 minutes a day, promises members: “It’s free and always will be.” It certainly sounds like a steal. But it is only one of the bargains that apparently litter the internet: YouTube watchers devour 1bn hours of videos every day, for instance. These free lunches do come at a cost; the problem is calculating how much it is. Because consumers do not pay for many digital services in cash, beyond the cost of an internet connection, economists cannot treat these exchanges like normal transactions. The economics of free are different.
Unlike conventional merchants, companies like Facebook and Google have their users themselves produce value. Information and pictures uploaded to social networks draw others to the site. Online searches, selections and “likes” teach algorithms what people want. (Now you’ve bought “The Communist Manifesto”, how about a copy of “Das Kapital”?)