Computer virus

Article By:

Mata-Toledo, Ramon A. Department of Computer Science, Rollins College, Winter Park, Florida.

Gupta, Pranshu Department of Mathematics and Computer Science, DeSales University, Center Valley, Pennsylvania.

Last reviewed:July 2021

DOI:https://doi.org/10.1036/1097-8542.154040

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• Computer virus, published June 2015:Download PDF Get Adobe Acrobat Reader

A program or script that is loaded and executed on a computer without the knowledge of the user. A typical computer virus is a very small program, several kilobytes or less in size, constructed in a matter of hours or days. When executed, the virus may generate undesirable results and may negatively affect the behavior of a computer. Viruses, also known as malicious programs (or malware), can create, move, and erase files; consume a computer's memory; capture confidential information; slow down a computer network; and replicate and send deceitful e-mail messages to other computers. A virus can not only harm the system on which it is saved and executed, but can also attach itself to another program and spread to other computers automatically. Computer security experts usually distinguish between types of malware with labels such as worms and Trojans on the basis of their different behaviors, since not all malware makes copies of itself and infects other computers, but the term virus is often loosely used to refer to all of them (Fig. 1). See also: Computer programming; Computer storage technology; Digital computer; Malware; Operating system; Software

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