Fifteen-year-old Rich Skrenta created an application called Elk Cloner as a prank—and ended up creating the first virus to spread outside its home network. Elk Cloner spreads via floppy disk and attaches to the Apple OS II operating system. When users boot from the disk, Elk Cloner transfers the computer's memory; any additional disks inserted without rebooting are also infected. On every fiftieth boot, the computer displays text written by Skrenta:

Elk Cloner: The program with a personality / It will get on all your disks / It will infiltrate your chips / Yes it's Cloner! / It will stick to you like glue / It will modify ram too / Send in the Cloner!