A computer virus is a computer program that can copy itself and infect a computer without permission or knowledge of the user.
A virus can only spread from one computer to another when its host is taken to the uninfected computer, for instance by a user sending it, via a program or file, over a network or the Internet, or by carrying it on a removable medium such as a floppy disk, CD, or USB drive.
History
There was an unsubstantiated rumor, circulating in the early seventies, about bored NASA programmers, with lots of spare time on their hands watching the early space modules traveling long distances, doing “battle” with each other, in the mainframe computers, with small programs.
Be this true or not, viruses, as we now know them, started appearing around the end of the sixties and beginning of the early seventies.
Initially, these viruses were more a nuisance than destructive. They would cause screens to appear upside down, characters to fall off screens and keyboards to miss random keystrokes.
However, they have become more malevolent and destructive.
The Virus today
They are now capable of:
Computer viruses are most commonly spread via:
Your can improve your chances of avoiding “infection “ by: