A computer virus is a self-replicating program designed to wreak havoc with computers. Some of them are benign, but mostly they're no laughing matter.

For example, the "Love Bug" virus, which appeared in early May, affected businesses and government agencies throughout the world. Many companies, large and small alike, had to shut down their computer systems to handle the attack, causing great economic losses.

How are these rogue programs able to creep into so many computers so quickly? To answer this, a little background information is needed.

A virus is meant to spread throughout one computer, often causing significant damage. It is not designed to spread from computer to computer, but if an infected file is copied from one computer to another via an external medium (diskette, CD-ROM, etc.), the virus can spread. Since it can only be transmitted via external media, it is slow to spread through an area, if it does spread at all.

A Trojan Horse acts like a regular virus, but is disguised as something useful, such as an image or extension file. When the user opens a Trojan Horse file, the virus is released into the computer, often causing significant damage. Trojan Horses cannot replicate themselves and therefore spread rather slowly.

A worm is a type of virus designed to be transmitted from computer to computer via a network (e-mail, for example), and can spread throughout an area much more quickly. Once it gets into one user's computer, it can attach itself to the e-mail program and send itself out to everyone on various distribution lists. The most recent virus threats to make the news—"Melissa" and the "Love Bug"—were actually worms. These two worms also had features of a Trojan Horse—the dangerous elements were contained within e-mail attachments.

For most people, the idea of deliberately creating an antagonistic computer program boggles the mind. Why would someone want to do this to other people's computers?

Viruses are created for various reasons—revenge, malice, political causes, boredom, spite, or even just for fun. People create them because they can, and they want to see what they can do. Unfortunately, some may not realize the full consequences of releasing viruses on the public. For everyone who wants to create a virus, there are several more people with the ability to track the virus' origin. And if the virus causes enough damage, the penalty can be harsh.

If you fall victim to a virus attack, there are several things you should do:

• If the virus is known to be transmitted within an e-mail attachment, do not open the attachment. Doing so will damage not only your computer, but can damage the computers of many others. Delete the e-mail without opening the attachment.
• If the virus is contained in an e-mail with a known subject, don't open the e-mail at all. Delete it right away.
• Make sure your virus protection software is up to date. Many new viruses are "immune" to older versions of anti-virus software.
• If you encounter a virus anywhere on your system, be sure to let your IT department know so they can take the proper measures to eliminate it and prevent it from spreading.
• Stay abreast of breaking virus news, so that you are prepared for any virus threats, or subsequent variations or copycats, headed your way.

There's no way to completely protect a computer from every virus out there or yet to come. More are being created and there will be more news of massive virus outbreaks. As technology advances, viruses may become stealthier, faster, and more destructive. The best way to stay ahead of them is to stay informed.