In June 2010, a computer virus called Stuxnet was found in electric plants and industrial complexes all over the world. The latest evolution of computer viruses eventually brought Iran‘s Bushehr Nuclear facility to a halt, in what many label as the first act of cyber ware by the use of the first Cyberweapon, Stuxnet.
A computer virus is a computer program that can replicate itself and spread from one computer to another. The term “virus” is also commonly, but erroneously used, to refer to other types of malware, including but not limited to adware and spyware programs that do not have a reproductive ability.
Viruses can increase their chances of spreading to other computers by infecting files on a network file system or a file system that is accessed by other computers.
Malware includes computer viruses, computer worms, Trojan horses, most rootkits, spyware, dishonest adware and other malicious or unwanted software, including true viruses. Viruses are sometimes confused with worms and Trojan horses, which are technically different. A worm can exploit security vulnerabilities to spread itself automatically to other computers through networks, while a Trojan horse is a program that appears harmless but hides malicious functions. Worms and Trojan horses, like viruses, may harm a computer system‘s data or performance. Some viruses and other malware have symptoms noticeable to the computer user, but many are surreptitious or simply do nothing to call attention to themselves. Some viruses do nothing beyond reproducing themselves.
Source: Source Wikipedia
Watch the Stuxnet – Anatony of a Virus!