What the difference between a trojan, virus and worm?
TROJAN A trojan is a network software application designed to remain hidden on an installed computer. Trojans generally serve maliciious purposes and are therefore a form of malware, like viruses. Trojans are similiar to worms. In contrast to worms and viruses, however, trojans do not replicate themselves or seek to infect other systems once installed on a computer. VIRUS A computer virus is a computer program that can copy itself and infect a computer without permission or knowledge of the user. Viruses are sometimes confused with computer worms and 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. Worm A computer worm is a self-replicating computer program.
A computer virus 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. A computer worm is a self-replicating computer program. It uses a network to send copies of itself to other nodes (computer terminals on the network) and it may do so without any user intervention. Unlike a virus, it does not need to attach itself to an existing program. 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. Unlike such malware, it does not propagate by self-replication but
