The first computer virus to openly make it to the public was a program called “Elk Cloner”. It was created by Rich Skrenta, a computer programmer who was in high school when this virs was created in 1982. Elk Cloner attached itself to the Apple DOS 3.3 operating system and was later spreaded by a floppy disk. When the virus was created, it was intentionally made as a joke by the high school student, who inputted the virus into a game in which the virus was set off after the 50th time of using the game. When the virus was set off, a blank screen appeared and displayed a poem about the virus. The computer then became infected.

The first PC virus was a boot sector virus named (c)Brain. Two brothers, Basit and Amjad Farooq Alvi, whose only intentions were to protect their work from piracy and to target copyright infringers, programmed it. However, according to analysts, the Ashar virus, which was a variant of Brain, possibly was created before the (c)Brain.

Before network computer expansion, most viruses were spreaded through removable media, such as floppy disks. These viruses infected programs stored in the disks, while others were inputted into the disk boot sectors, and activated when the user booted the computer from the disk. The traditional and typical virus characteristics common to us now emerged in the 1980s, where there was an increase of BBS (Bulletin Board System, where a computer system runs software that allows users to dial into the system over a phone line), modem use, and software sharing. BBS contributed greatly to the rapid spread of Trojan horses, and viruses were orginally written to target popular software traders. Traders who were in a hurry to retrieve the lastest software were usually the easiest prey to infect viruses with.

In the mid 1990s, macro viruses came into the scene and became common quickly. Ironically, some versions of Microsoft Word allowed the macro virus to multiply and gain additional blank lines. This can cause a misleading detection, as others would see the new strands of the macro virus as a new virus.

Viruses then began spreading via instant messaging. Typically, it sends a web address to everybody in the contact list, and anyone who so much as click on the link would be prone of an immediate infection. However, there are thousands and thousands of viruses operating online and new viruses are discovered every single day.