My daughter has put her details online. Should I worry? ; Cyberclinic

It's relentlessly drilled into us to be careful when using creditcards on the internet. But a recent survey by the security expertsSymantec showed that one in 10 people are comparatively cavalierwhen it comes to revealing other kinds of personal information onblogs and social networking profiles. I'm as bad as anyone; althoughI'm not stupid enough to reveal my mother's maiden name on a dailybasis, I do allow sites to tease personal information out of me andput this information on display to the world - such as my birthday.And I'm not alone.

"It didn't occur to me until I read this week's question,"emailed John Freeman, "that my complete schooling history featureson at least two popular websites."

Parents seem to be primarily concerned that this information leakmight lead their offspring to become victims of stalking. In truth,the younger generation are far better at concealing their identitieswhile online than their parents are. But surveys show that around 2per cent of us have, nevertheless, experienced some kind of onlineharassment, with 7 per cent of those cases having spilled over intothe real world.

The impact of this is hard to measure; even though these stalkersare unlikely to end up loitering outside your flat, it can bedistressing. "Ever since I had a bombardment of unpleasant emails acouple of years ago," writes Clare S, "I've been much more carefulwith MySpace profiles and so on - particularly with photos. And ifyou have a choice of whether or not to reveal certain information,I'd advise just to click on 'no'."

From swivel-eyed stalkers to identity fraudsters: they can usesimilar information to obtain store cards, personal loans and evenmortgages in our names. And it's worth stressing that these aren'tcrack teams of geeks hacking their way through firewalls, they justhave internet access, a bit of spare time and criminal intent.

Tom Ilube, of "identity guardians" garlik.com, explains:"Recently, from one girl's Myspace page, I was able to follow linksand obtain her surname, date of birth, address and mother's maidenname - all quite legally, and within about 30 minutes. While thisinformation can't be used to hack into an online banking account, itcan still be used for fraudulent purposes." If you're worried aboutcompromising information that may already be online, garlik.comoffers a service called DataProtect which scours the internet andthen offers you advice - depending on the information that itmanages to unearth. But a good first step might be to forego a few"Happy Returns" wishes from complete strangers, and delete your dateof birth from Facebook. Just to be on the safe side.