How an Antivirus Program Works

From the early viruses, created as experiments in the eighties, to the latest malicious code, one of the biggest worries for all computer users is the threat of viruses entering their systems.

To prevent viruses from entering a system there are basically just two options. The first of these is to place the computer in a protective 'bubble'. This in practice means isolating the machine; disconnecting it from the Internet or any other network, not using any floppy disks, CD-ROMs or any other removable disks. This way you can be sure that no virus will get into your computer. You can also be sure that no information will enter the computer, unless it is typed in through the keyboard. So you may have a fantastic computer, the perfect data processing machine...but with no data to process. If you're happy with that, your computer will be about as much use as a microwave oven.

The second option is to install an antivirus program. These are designed to give you the peace of mind that no malicious code can enter your PC. But how do they do it? How does the program let you install a game, but prevent a virus from copying itself to disk? Well, this is how it works....

An antivirus program is no more than a system for analyzing information and then, if it finds that something is infected, it disinfects it. The information is analyzed (or scanned) in different ways depending on where it comes from. An antivirus will operate differently when monitoring floppy disk operations than when monitoring e-mail traffic or movements over a LAN. The principal is the same but there are subtle differences.