Virus A computer program file capable of attaching to disks or other files and replicating itself repeatedly, typically without user knowledge or permission. Some viruses attach to files so when the infected file executes, the virus also executes. Other viruses sit in a computer's memory and infect files as the computer opens, modifies or creates the files. There are computer viruses written for several operating systems including DOS, Windows, Amiga, Macintosh, Atari, and UNIX, and others. Virus Hoaxes Hoaxes are not viruses, but are usually deliberate or unintentional e-messages warning people about a virus or other malicious software program.
Some hoaxes cause as much trouble as viruses by causing massive amounts of unnecessary e-mail.
If you receive an e-mail message about a virus, check with a reputable source to ensure the warning is real. Sometimes hoaxes start out as viruses and some viruses start as hoaxes, so both viruses and virus hoaxes should be considered a threat. Worm Worms are parasitic computer programs that replicate, but unlike viruses, do not infect other computer program files. Worms can create copies on the same computer, or can send the copies to other computers via a network.