Today’s steam engines are social media. Mark Zuckerberg wasn’t the only person to come up with the idea of an online social network; in fact, he wasn’t even the only Harvard student to think of it. But whereas Facebook is set to become one of the most highly valued companies on the planet, its precursors are at best settling into early retirement; at worst, they have gone out of business.

So why did Facebook succeed where others, including SixDegrees.com, tribe.net, Friendster and MySpace, failed? To be sure, some vital precursor technology was lacking, particularly the computational horsepower needed to reveal your friends-of-friends-of-friends. And internet anonymity was still the order of the day when many of these fledgling services were trying to establish themselves. Early adopters and exhibitionists aside, many potential users were more comfortable goofing off under fake identities than entrusting information about their real lives to corporate servers. In short, it wasn’t their time.

It certainly seems that it is Facebook’s time now: the network is heading fast for its billionth member. What’s more, Facebook has a history of trying to rush us into its own timescale. You may not think it’s time for location-based services, face recognition or automated diary planning, but Facebook thinks differently. So far, it seems that users have the upper hand: the giant firm has repeatedly introduced services only to pull them back again. But such innovations often return – when the time is right.