Why we have viruses is a difficult question to answer. Why do some people spraypaint graffiti or make prank phone calls?Many viruses are written by young computer adventurers, testing and expressing their programming skills and their curiosity to see what can happen.

Some do it to gain knowledge, some for fame, and some to prove themselves worthy to join underground virus gangs. Others may write viruses because they seek attention, revenge, or the challenge to defeat antivirus software. Other virus creators may be bored, vandals, or sociopaths.

The possibilities are endless. Some virus writers don’t create viruses from scratch. In many cases, they’ll take an existing virus and add or change a small part of it, thereby creating a new virus, resulting in a twisted sort of virus evolution.

Some conspiracy theorists speculate that the antivirus software makers also write some of the viruses. That certainly would help boost the sale and dependency of antivirus software. However, there has never been any evidence that this has occurred.

Here are some general guidelines that will help you to avoid getting a virus:

• Install antivirus software and keep it updated.
• Since most viruses are spread through e-mail, don’t accept files or programs from people you don’t know.
• Never activate any file that arrives in e-mail, even if it is from someone you know, unless you have up-to-date antivirus software running at all times.
• When uncertain about a file sent by e-mail, assume it’s a virus.
• Only download files that are from a legitimate and respectable source.
• When starting your computer, make sure there are no floppy disks inserted into the floppy disk drive.
• Keep your Windows operating system updated with the latest security fixes (discussed in detail next).
• Make sure your computer is free of viruses before you back up your data; otherwise, you may be backing up the virus, too!

The two most successful and reliable antivirus programs are McAfee VirusScan and Norton AntiVirus. Figure 2-4 shows an example of a Norton AntiVirus window.

While there are literally dozens of antivirus programs available, these are the two that detect the largest number of viruses consistently. Not all antivirus software is created equal.

If you simply cannot afford to buy either the McAfee or Norton program, you can download a fully functional copy of AVG antivirus for free from www.grisoft.com. It may not be as refined or as reliable as the commercial programs, but something is better than nothing.