The dirty half-dozen

A VIRUS is a program that reproduces its own code by attaching itself to another program. It is basically a self-replicating program written for destructive purpose. It interferes with the computer's operating system (the basic software that runs the computer). Viruses are designed to replicate and elude detection. Like any other computer program, a virus must be executed to function -- that is, it must be loaded from the computer's memory, and the computer must …

…executable code - that run programs are exchanged from one computer to another. It can be through infected floppy or CD or through infected e-mail. Through these mediums, the virus copies itself to the other computer without the knowledge of the user. A virus upon entering a system first monitors the system and then activates itself at a proper time to cause maximum harm to the information stored on to the computer. cite - tribune