Virus
What is a virus?
A computer virus is a computer program that can copy itself and infect a computer. The term “virus” is also commonly but erroneously used to refer to other types of malware, adware, and spyware programs that do not have the reproductive ability.
http://en.wikipedia.org/wiki/Computer_virus
http://www.microsoft.com/security/antivirus/whatis.aspx
Tip: You must have valid antivirus software installed on your PC.
