What is a Virus?

Introduction to Computer Viruses

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What is a virus?

A computer virus is a program that can make copies of itself. Most computer viruses do nothing more than this and are more of an annoyance than a danger. Some computer viruses, though, may also harm data and programs stored on a computer.

What types of viruses are there?

What is not a virus?

Trojan horse programs are designed to do something (usually something malicious) other than their supposed purpose. Trojan horse programs are sometimes classified with viruses. However, because they don't make copies of themselves, they are not true viruses.

Some programs are designed as a joke, or prank, but are not viruses. For instance, warnings of a virus incorporated in a mail message with the phrase "Good Times," "Join the Crew," or "Penpal Greetings" in the header have, at times, been rampant. The only thing that spreads, however, with these "viruses," is the messages warning people to look out for the supposed virus in their e-mail. And, it's the person sending the message, not the computer, that causes the message to be copied and spread.

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Last modified: November 25, 1997
This page maintained by Beth Miller.
Copyright © University of Delaware 1997.