What is a computer virus? A computer "virus" is a program used to infect a computer. A computer "virus" frequently alters and/or erases critical files on a fixed disk or diskette. A computer virus may be resident on a fixed disk or diskette and go unnoticed for a period of time. During this time, it can be transmitted to other systems (usually by software copied from one system and loaded on another). The virus can go unnoticed because some viruses are written to corrupt files at a certain time in the future. A virus is only passed along when a program that contains one is executed on your computer. A virus cannot attach to data; they must attach to an executable program on a PC. For the virus to be activated, the program to which the virus has attached itself must be run. When the program is executed, the virus code is activated and attaches copies of itself to other programs in the computer. The virus may also be transferred to system memory and remain there until the system is powered off. Any program that is executed while the virus is in the system memory may become infected. The majority of viruses that are contracted on personal computers are passed along through "hand-to-hand" exchange of software via a diskette. Also, virus infected programs are sometimes unintentionally transmitted via modem from public bulletin board services, online services, or the Internet. If you use software that has been downloaded copied from another computer, you may wish to obtain a virus-detection program. You can edit the AUTOEXEC.BAT file on your computer to load a virus scanning program. Doing this means that you cannot start the computer without running the virus scanner. It is also a good idea to scan diskettes that have been used on other computers before using the diskettes on your computer. This is especially true if you are using diskettes on a computer that many other people also use, for example in a computer lab on a high school or college campus. For safety's sake, it is also a good idea to always have a current BACKUP of your fixed drive. If you take the necessary precautions, you should not have to worry about viruses infecting your system. While IBM cannot recommend a single AntiVirus application for your use, two of the most popular programs are Symantec's Norton AntiVirus and McAfee VirusScan. Norton AntiVirus is available online at www.symantec.com McAfee VirusScan is available online at www.mcafee.com Please be sure to keep your virus definition up to date, as new virus' are discovered every day. Click here to obtain assistance updating Norton AntiVirus virus definitions.