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Trojan horse

In the context of computing and software, a Trojan horse, or simply trojan, is a piece of software which appears to perform a certain action but in fact performs another such as a computer virus.

Contrary to popular belief, this action, usually encoded in a hidden payload, may or may not be actually malicious, but Trojan horses are notorious today for their use in the installation of backdoor programs.

Simply put, a Trojan horse is not a computer virus in most cases. Unlike such malware, it does not propagate by self-replication but relies heavily on the exploitation of an end-user (see Social engineering).

It is instead a categorical attribute which can encompass many different forms of codes. Therefore, a computer worm or virus may be a Trojan horse.

The term is derived from the classical myth of the Trojan Horse.

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Désiré has been musing and writing about technology during a career spanning four decades. He dabbled in website building and web hosting when DHTML and frames were en vogue and started writing about the impact of technology on society just before the start of the Y2K hysteria at the turn of the last millennium. Following an eight-year stint at ITProPortal.com where he discovered the joys of global tech-fests, Désiré now heads up TechRadar Pro. Previously he was a freelance technology journalist at Incisive Media, Breakthrough Publishing and Vnunet, and Business Magazine. He also launched and hosted the first Tech Radio Show on Radio Plus.