The computer virus celebrates its 25th birthday today, having made its first appearance in 1982 on Apple II computers. 


According to Scientific American, the first virus – Elk Cloner – was more irritating than anything else, displaying a short poem that promised to infect the whole computer.
Written by a high school student, the virus was spread on floppy disks bearing Apple II games, so it wasn't very prolific.
The first IBM PC virus was released in 1986.
In the 25 years since their first appearance, viruses have gone beyond minor irritant to big business, with malware now available to steal anything from data to money to identities.
The Elk Cloner poem read as follows:
"It will get on all your disks
It will infiltrate you chips
Yes, it's Cloner! …"