Computers can process information only if it is first converted into digital form. This digitisation has many benefits. It makes it easier to manipulate data, make its unlimited copies by a simple command and transfer the files from one place to another on portable storage devices or even send it across the wires instantly to computers far away. However, this ease of replication of data and its ability to travel long distances give rise to a threat that can destroy it all ? computer viruses.

Computer viruses cause immense damage each year worldwide causing tremendous financial losses running into billions of dollars. As a result, a whole new industry has cropped up that specialises in making software tailored to neutralise the threat posed by these viruses. Dozens of new computer viruses are generated each month the world over. The anti-virus software companies identify and catalogue the codes of these, incorporate them in their software package and keep their databases fresh and updated so that they manage to recognise and remove latest viruses that are always coming into circulation.

But what are computer viruses anyway? A virus is nothing but a small software programme written with malicious intent. It has instructions which, when executed on a user's computer, can cause harm to the data. It may corrupt software files, alter their code and make them unreadable.

There are viruses that are programmed to reformat your entire hard disk without your permission and purge it of all stored data! Some of them may force you to do certain tasks repeatedly ? such as pressing a button on the key board every 5 minutes ? that cause irritation and do not allow you to concentrate on your work.

Since viruses are software programmes ? small lines of computer code ? they obviously have to be written by people who know software programming. These are often teenagers or college students who get a kick out of creating something that gives them a sense of power over others.

When rogue programmers see the virus they wrote spread all over the world and cause damage to millions of computers, they get an adrenaline rush because the episode confirms to them their intellectual superiority and boosts their ego. Some programmers are just mischievous sadists who get a thrill out of causing damage, destruction and inconvenience to citizens at large. Most countries have strict cyber laws that make creating and spreading viruses a crime.

A couple of decades ago when Internet was in its infancy, viruses used to spread themselves by getting copied to removable storage media such as floppy disks and compact disks. All one had to do was run an anti-virus check on each floppy or CD before accessing them and the computer used to remain safe from infection. With the coming of the Internet, however, viruses now mostly spread online.

Whenever you download an attachment to your hard disk from the Internet, there is a risk of a virus (or its variants such as Trojans and worms) copying itself to your computer. Some viruses may without your permission quietly download themselves on your hard disk as you go about browsing harmless-looking websites. This can be a dangerous situation for the health of the data residing on your computer. To prevent this, you should always have an anti-virus solution from a reputed company such as Norton or McAfee running in the background, monitoring all downloads and files being copied to your desktop.

The moment the software spots a virus, it issues a warning and neutralises the threat. Whenever you go online, the anti-virus automatically downloads latest virus definitions from its official website and updates its library, thus keeping you safe from latest viruses that have got created since you bought the software.

If a virus strikes, you should immediately run a good anti-virus software package. These ?vaccines? scan the entire hard disk and other storage devices attached to your computer, identify hidden viruses, Trojans and worms and present their names to you for necessary action.

You can then clean the infected files of the viruses. The files that cannot be cured and remain infected are quarantined and not allowed to be used by the operating system. Even otherwise, it is a good idea to scan your entire computer through an anti-virus package at least once every week so that your precious data remains safe and secure.