It was written around 1982 by programmer and entrepreneur Rich Skrenta as a 15-year-old high school student, originally as a joke, and put onto a game disk.
Elk Cloner spread by infecting the Apple DOS 3.3 operating system using a technique now known as a boot sector virus.
At set numbers of times the disk's program had been run (all multiples of 5), it would cause various strange behaviors of the Apple II, many requiring a reboot to correct.
In sharing computer games and software, he would often alter the floppy disks to shut down or display taunting on-screen messages.
He developed what is now known as a boot sector virus, and began circulating it in early 1982 among high school friends and a local computer club.