Elk Cloner: The First Computer Virus.

The title of first computer virus is usually given to Elk Cloner, created in 1982 by a 15-year-old high school student named Richard Skrenta.
Elk Cloner was not malicious like modern viruses. Instead, it was more of a prank. It spread through Apple II floppy disks and, after every 50th boot from an infected disk, it would display a playful poem on the screen. The virus attached itself to the operating system stored on floppy disks, so whenever someone used an infected disk, it would quietly copy itself onto other disks, spreading from one computer to another.
Though Elk Cloner wasn’t harmful, it showed how software could self-replicate and spread — laying the foundation for how we understand computer viruses today. The first PC virus came later, in 1986, known as Brain, created in Pakistan.