As the personal computer gained prominence in the early 1980's, so did the computer virus.
Several theories exist as to the exact date and origin of the first virus to exist in the wild.
Today, over 40,000 computer viruses are in existence. With such a proliferation, lines have begun to blur as to what constitutes a computer virus. To qualify as a virus, it must self-replicate, i.e. create copies of itself to continue the infection. The program in which the virus is hidden is referred to as the host. Trojan - A Trojan Horse is a program that does something other than what it is advertised or believed to do.