A Brief History Of Viral Time

For about 20 years now we've been using the term computer viruses to describe self-replicating programs. Although such programs had previously been found on Apple computers, viruses entered the PC world in early 1986 with the Brain virus.

		20 Years Of PC Viruses
		Introduction  A Brief History Of Viral Time       •  The Early Years       •  Viruses Get Smarter       •  Enter The Internet       •  Today's Malware  The 10 Most Destructive Viruses  Early Days On The Antivirus Front  What To Do In A Malware Attack
		Virus Image Gallery

Created by two programmers named Basit and Amjad, Brain was a boot virus that ran when a computer was booted up with an infected floppy diskette in the A: drive. (Remember when floppy disks were actually floppy?) Once a machine was infected, it would infect all subsequent floppies put in the drive.

Brain, a.k.a. (C)Brain, was also the first stealth virus, meaning that the boot sectors of infected diskettes would appear uninfected to users. The Brain virus didn't spread very quickly, nor was it particularly harmful -- but it ushered in an era of increasingly destructive viruses, worms, and other malware.

Computer viruses have changed a great deal since then. It has generally been an evolutionary change: mostly small developments that, when looked at cumulatively, can be viewed as rather spectacular. In this story we'll look at overall trends in the history of PC viruses; also see the timeline below and to the left (requires Flash) for more information about specific virus events.

	Virus Or Worm?
	In this piece we use the term virus generically to mean any self-replicating software. Technically, though, a virus uses a computer's storage media -- hard disk, floppy disk, flash memory stick, etc. -- as its transfer medium, whereas a worm uses external resources, such as an Internet connection or a network server. Additionally, viruses usually need some form of user interaction to spread, while worms may spread with no user assistance. The term malware refers to any kind of malicious software, including viruses, worms, Trojans, spyware, rootkits, and so on. We'll get to these other nasties later in the piece.