Trojan Horse Definition

Trojan Horse A computer program is either hidden inside another program or that masquerades as something it is not in order to trick potential users into running it. For example a program that appears to be a game or image file but in reality performs some other function. The term "Trojan Horse" comes from a possibly mythical ruse of war used by the Greeks sometime between 1500 and 1200 B.C.
A Trojan Horse computer program may spread itself by sending copies of itself from the host computer to other computers, but unlike a virus it will (usually) not infect other programs.