A computer virus is defined as a software program capable of reproducing itself and usually capable of causing great harm to files or other programs on the same computer. The existence of computer viruses--or the necessity of avoiding viruses--is part of using a computer. With the advent of the Internet, the door was opened wide for these infectious malcontents. This article offers a few steps to protect computers from viruses: (1) Do not let down your guard; (2) Do not put your faith in firewalls; (3) Do not put your faith in anti-virus software; and (4) Do not forget operating system updates.