The widespread use of computers has far-reaching implications for the structure of our society. On the one hand, we have the benefits; menial office tasks are mostly computerised so we can concentrate on important work, we can communicate easily with people all over the globe, complex mathematical problems can be solved quickly which helps advance scientific research, and there's easy access to pornography. And, on the other hand, we have the disadvantages; menial office tasks are mostly computerised so more important work is expected to be done, people from all over the globe can communicate with us whether we like them or not, scientific research is taking us down roads that some would rather not take, and there's easy access to pornography.

So much for philosophy. There's one aspect of the computer revolution that goes largely unnoticed, but has serious implications for all of us, and at its heart is the humble database. Yes, the database. Originally designed to store large quantities of tedious information in an easily-retrieved format - stock control systems, pension information, that sort of thing - databases can just as easily be used to keep track of humans. And, increasingly, that's exactly what they are being used for. You may not realise it, but every time you use a credit card, or even a store 'loyalty' card, the chances are that the information about your purchase is being stored on a database and correlated with other information known about you. Your age, social status, marital status, occupation, buying habits and so on are all combined until the database owner has a pretty complete image of you, and it's probably not a flattering one. Often it's not even accurate, but that won't stop the company either tailoring specific targeted marketing material (i.e. junk mail) to you, or selling the details to someone else.

It doesn't stop there. In many urban areas, there are surveillance cameras in shops, bars, public transport systems and streets. There are even some in the toilets of office buildings, although it's not something you'd discover too easily. Increasingly, our everyday activities are being watched and recorded. A trial system is being introduced in some parts of the country to identify known offenders, using a network of cameras, a database of photographs and some face recognition software. Regardless of the implications for civil liberty, let's just hope it's accurate.

None of this would have been possible before computers became so prevalent. The work involved would have been far too time-consuming. But should you care about the information being stored about you? Yes and no. Targeted marketing material has to be better than the usual junk mail, but unsolicited phone calls offering double-glazing or time-shares quickly become irritating. And the idea of being watched all the time is not a particularly comforting one. It may be irrational, but perceived loss of privacy can, for some, be synonymous with loss of identity. Still not worried? Perhaps you use a computer at work. Perhaps you spend some of your work time playing games, or downloading pictures from www.pendulousjugs.com. Perhaps you aren't aware that software exists to track, record and report on user activity within a network. Perhaps you'll become aware of that at your next appraisal. Big Brother is alive and well, and he's not playing Quake.