Cybercrime is one of the fastest-growing criminal activities on the planet. It covers a huge range of illegal activity including financial scams, computer hacking, downloading pornographic images from the internet, virus attacks, stalking by e-mail and creating websites that promote racial hatred.
Cybercrime is defined by British police as the use of any computer network for crime and the high-tech criminals of the digital age have not been slow to spot the opportunities.
The cost is staggering. The German foreign minister Joschka Fischer recently put the global figure at more than $40bn a year. "Without doubt, this is only the beginning," he told an international conference. "Data espionage and data theft, credit card fraud, child pornography, far-right extremism and terrorists are ever more common on the internet."
Given the extent to which computers have become a part of modern life, it was inevitable that some people would see the wired world as an opportunity to make money or cause mischief.
The term hacking was originally used to describe an audacious practical joke, but has become better known as a term for the activities of computer enthusiasts who pit their skills against the IT systems of governments and big corporations. The handiwork of some hackers, or "crackers" as they are known in the computer industry, has had disastrous results. The "love-bug" virus crippled at least 45 million computers worldwide and caused billions of dollars worth of damage.
Then there is fraud and extortion. Some hackers have broken into the computer systems of banks and other businesses, with the intention of stealing money - or information like credit card numbers, which are just as valuable to the criminal.
90% of US companies which responded to a Computer Security Institute survey said they had detected computer security breaches in the previous year
74% acknowledged financial losses as a result of the breaches of security
273 organisations quantified their financial losses: the total bill came to $265m.
25% of respondents detected penetration from outside their company
79% detected employee abuse of the internet, for example downloading pornography or pirated software
85% detected computer viruses
Source: CSI/FBI Computer Crime and Security Survey, 2000
CSI director Patrice Rapalus believes the trends are disturbing. "Cybercrimes and other information security breaches are widespread and diverse," she says.
Scams by cyber-criminals include setting up bogus companies on the Net. Unsuspecting buyers are offered products at tempting prices, and then supply their credit card details - only to find that the site suddenly disappears. No phone number, no address and no redress. The dot com becomes a dot con.
Another 21st century crime is identity theft. This usually does not involve hacking at all. Criminals can trawl the web or other public databases for information about someone's date of birth, social security number and address and then use that to apply for credit cards and run up huge bills. It is easy to do and as a result is one of the fastest growing crimes in the US.
The availability of hard-core pornography on the internet, including material aimed at paedophiles, has helped to give it a bad name. But it is not just the police who are cracking down - many companies now routinely monitor the sites their employees visit online, and those who download pornography run the risk of being fired.
World without boundaries
In the UK, the National Criminal Intelligence Service has compiled a report on the threat of cybercime called "Project Trawler". Director of Intelligence, Roger Gaspar, says the internet has eroded the protection provided by national laws against such activities as pornography.
"The internet is a global system," he says. "We can now be attacked by criminals who do not need to come to this territory. Lots of policing arrangements have their roots in the fact that victim and offender are geographically co-located.
"It is a different world now, and if you can do your business legitimately from home via the electronic medium, why can't that business not be criminal business? We have to move ourselves into this new world. It is a great challenge for us."
So the problem for all law-enforcement agencies is the way that cybercrime, like the internet itself, is not limited by national boundaries. An investigation that begins in one country may quickly lead elsewhere, but without the co-operation of other nations, it may be impossible to track down the perpetrators and secure convictions.
In the UK, the government is making more cash available to the police and other agencies to target cybercrime. The National Hi-Tech Crime Unit is being set up with the intention of making the UK one of the safest places in the world to take part in e-commerce. A team of "cyber cops" will help to police the internet.
Announcing the plan, the Home Secretary, Jack Straw, said: "Modern technologies such as the internet offer up huge legitimate benefits, but also powerful opportunities for criminals, from those involved in financial fraud to the unlawful activities of paedophiles.
"The significant cash injection I am announcing will boost the police service's capability to investigate crime committed through computers, including paedophilia, fraud, extortion and hacking."
Questions of liberty
The FBI has a Computer Crime Squad with more than 200 agents across the United States. It makes use of informants and under-cover agents. It says the problem is no longer confined to juvenile hackers; professional criminals are now exploiting the internet for profit.
Recent virus epidemics around the world, and attempts to extract money or data from major corporations, have demonstrated just how much damage such attacks can cause, and cybercrime is now being taken very seriously at an international level.
But when the Council of Europe produced a draft treaty on cybercrime, it was deluged by e-mails from internet users concerned about possible infringements of their privacy and liberty.
One complaint said that the proposals could have "a chilling effect on the free flow of information and ideas."
European officials say they have tried to address these concerns, and stress that their intention is simply to consolidate laws against activities such as hacking, spreading viruses, and computer fraud so that in future there is a standard way of securing the digital evidence needed for prosecutions.