Computer virus: Difference between revisions

Revision as of 18:52, 9 April 2008

Revision as of 12:22, 10 April 2008

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A '''computer virus''' caca is a [[computer program]] that can copy itself and infect a computer without permission or knowledge of the user. However, the term "virus" is commonly used, albeit erroneously, to refer to many different types of [[malware]] programs. The original virus may modify the copies, or the copies may modify themselves, as occurs in a [[Metamorphic code|metamorphic virus]]. A virus can only spread from one computer to another when its host is taken to the uninfected computer, for instance by a user sending it over a network or the Internet, or by carrying it on a removable medium such as a [[floppy disk]], [[Compact Disc|CD]], or [[USB flash drive|USB drive]]. Meanwhile viruses can spread to other computers by infecting files on a [[network file system]] or a file system that is accessed by another computer. Viruses are sometimes confused with [[computer worm]]s and [[Trojan Horse (Computing)|Trojan horses]]. A worm can spread itself to other computers without needing to be transferred as part of a host, and a Trojan horse is a file that appears harmless. Both worms and Trojans will cause harm to computers when executed.

Most personal computers are now connected to the Internet and to [[local area network]]s, facilitating the spread of malicious code. Today's viruses may also take advantage of network services such as the [[World Wide Web]], [[e-mail]], [[Instant Messaging]] and [[file sharing]] systems to spread, blurring the line between viruses and worms. Furthermore, some sources use an alternative terminology in which a virus is any form of self-replicating [[malware]].