Spyware has become well-engrained in the day-to-day vocabulary of many computer users. The number of attacks is rapidly increasing, with an estimated 31.7 per cent of all PCs in the UK currently infected with some form of spyware. Worse still, it is said that a brand-new PC will fall victim to spyware after just 30 minutes of internet connection.

It is important to understand the difference between spyware and a virus. "Spyware is about harvesting information: log-in passwords, account information, your surfing and shopping habits," said Daniel Mothersdale, Webroot's marketing director, EMEA (pictured). "It is a type of system monitor, grabbing your details, using them and then selling them on."

Spyware comes in many different formats, some obviously more complex and threatening than others. There are cookies and adware at one end of the spectrum, Trojans on the next level, and rootkits at the upper end.

"Rootkits have become increasingly prominent over the past six to nine months. There are some very clever ones that go onto your PC and lie dormant. Two or three weeks later they will bring in another file, which will also sit inactive. Then they go and get a third file and, when the three files are there, they will activate each other and release the spyware on to your PC," explained Mothersdale. "Getting rid of these files poses a particular challenge. We've known some files that simply multiply the more you try to break them up."

In EMEA, 80 per cent of PCs host at least one of the above types of spyware. But where does it all come from? According to Mothersdale, a simple typing error, such as "www.googkle.com", can lead to an infestation. "When you go to that site, it looks and works like Google, but when you start using it, you get a ton of spyware coming onto your PC immediately. USB sticks and CDs are other great ways of transferring these system monitors."

Over the course of 2006, worldwide sites propagating spyware have quadrupled to around 523,000. System monitors are increasing by 50 per cent quarter on quarter and are becoming more complex.

"The people in charge of these attacks have no shame. They'll attack anyone to make a bit of money. The average piece of information, such as credit card details, passes through five hands in less than 72 hours. It starts at £10 and ends up costing less than 50p," warned Kevin Roberts, managing director, EMEA, at Webroot.

"The impact of these attacks can be destroying. If you attack Barclaycard, they lose their reputation. But if you attack a small company, chances are it will have no business left the following morning," he added.

Protecting yourself against these viruses isn't easy. Detecting the spyware is the first hurdle, as they are not made for easy discovery. It is then necessary to block the item and fully remove it from the root of your PC to ensure it does not return when you restart your machine. Not all anti-spyware products do these three things, and Mothersdale recommends investing in a best-of-breed brand.

"There are several ways to protect yourself against spyware," he says. "First, make sure your firewall is turned on. Next, buy an anti-virus and an anti-spyware product - one that detects, blocks and removes the problem - and again, have it switched on. Then ensure you keep these programs regularly updated. "Finally, be paranoid. This way you won't be leaving yourself open for attack. It's one of the best forms of preparation there is," he said.

Contact details: tel 0845 838 1130; www.webroot.com/uk.