What is a virus? The term broadly describes any program that tries to hide a malicious function or spread copies of itself on to as many computers as possible.

Believe it or not most viruses are benign, displaying a message or picture at a specific time. There are some malignant viruses that can cause damage to your files and programs. Most viruses in circulation fall into six key classifications:

1. Worm a self contained program that can spread functional copies of itself to other computer systems.

2. File Infector attaches itself to ordinary program files, it usually ends in exe or com.

3. Trojan Horse Noramlly a non-replicating program, designed to perform malicious damage, such as destroying all word processing documents.

4. Boot Sector Infectors These attach themselves to the boot sector of a disk, either on your hard drive or on any floppy disk that you insert into your floppy drive.

5. Master Boot Record Infectors Infect the master boot program preventing it from starting in the usual way, for example constantly restarting.

6. Multi-partite viruses this can infect both the master boot records, or files and disk boot sectors.

How does your PC pick up a virus? They dont just occur, they are introduced to your PC by an outside party and can be avoided if you take approriate precautions.

Downloading files from the internet or receiving e-mail can put you at risk of virus infection. Contrary to popular opinion its not generally possible to contract a virus by simply reading an e-mail message. The damage is done by executing files that are attached to your message without first checking for viruses. This could also occur by importing information from floppy disk files that were created on an infected PC.

How do I know if I have a virus? Generally, some of the symptoms might be a discrepancy in the amount of memory you have, running out of hard drive space unexpectedly, programs running or loading slowly, unidentified files appearing, and unexpected crashes or failure to load. These symptoms could also be due to a number of common technical problems, dont automatically assume that you have a virus the moment anything looks out of the ordinary or slows down.

The best way to ensure protection from viruses is to install a specialised piece of software often referred to as anti-virus software or a virus checker. This continually scans for possible problems and alerts you before they can inflict any damage.

If the suspected virus is one that has been identified by the manufacturers of your software you can often fix the problem immediately. Set your virus checker to scan all e-mail and downloads from the internet, as well as scanning any floppy disks in your disk drive.

Virus checkers work by identifying and eliminating known viruses. So it is very important to keep your records up to date using the free update facility provided by most reputable companies. Many anti-virus programmes have an automatic update facility so that when connected to the internet you can download updates straight onto your PC.

There is today a phenomenon known as Hoax Virus alerts these may be borne out of media coverage or isolated extreme cases. You will now find teat the major anti-virus companies now also keep a list of Hoax Viruses so users can identify the validity of an e-mailed virus alert immediately.

If you're careful theres little chance of you experiencing a PC virus. Even if you contract an unidentified strain your virus-checker will know its a suspicious file and should isolate it until its origin can be confirmed.

Regularly creating backups will help limit the damage done in the event of your contracting a destructive virus.

There are thousands of computer viruses, but only a few pose a significant threat to the home PC user. Any that do find their way into your PC system can usually be eliminated quickly using an up to date virus checker. So that the probability of experiencing any adverse effects is lower than the media coverage would lead you to believe. Most cases of infection are caused by an infected floppy disk being left in the disk drive, so remove these as soon as you have finished using them.

Finally, if you receive e-mail that I suspicious or you dont recognise the sender, dont open it delete it straight away and dont open any attachments with it. No system can be a 100% fireproof against viral infection but it is just like having an inoculation with it the risks are reduced, without it the risks are higher, prevention is far better than cure.