Leading article: Face up to the future

When Mark Zuckerberg launched "The Facebook" in his Harvard dormitory five years ago, he hoped the new website would help his fellow students stay in touch and get to know each other better. But it was not just the elite of this Ivy League bastion whose social lives were destined to be revolutionised by Mr Zuckerberg's invention.

Facebook, the biggest social networking site, has 150 million users. The music-orientated MySpace is not far behind with 130 million. Meanwhile, Twitter, a stripped-down variant of the networking site, is growing rapidly too. In five years, these sites have become an entirely new global communications platform. No wonder they have been courted by advertisers. But does the boom of the sector have any wider social utility? Enhanced human contact is the obvious answer to that. These sites allow people to stay in touch in a hectic and busy world. Friends across the globe are accessible with the click of a mouse. The sites are also helping to re-engage some people with politics. Barack Obama's presidential campaign managed to harness such sites with considerable success.

Yet there are potential hazards. One of the reasons Facebook outperforms its peers is that it offers the security of being part of a private community of friends. But many users had a rude awakening two years ago when it emerged that Facebook was automatically advertising their purchases online. Sometimes, there is such a thing as too much shared information. Likewise, few users grasp just how much information Facebook and other sites have compiled about them for the purposes of selling it on to advertisers. It is possible that some heavy social networkers will come to regret invading their own privacy quite so enthusiastically in years to come.

That said, nigh on every new popular technology, from the motor car to the mobile phone, came with certain hazards. They survived because their utility manifestly outweighed their drawbacks. At the moment, social networking sites seem to be fulfilling a burgeoning demand for people to talk to each other online. For now, the revolution continues.