1949: John von Neumann writes “Theory & Organization of Complicated Automata,” which theorizes about computer programs that reproduce.
1960s: The game Core War is developed players write programs that do battle with each other in a simulated computer. It’s a hit with extreme geeks in the academic & military sector.
1981: Disruptive adolescent Rich Skrenta writes the 1st microcomputer virus released into the wild, Elk Cloner. It continues to crop up on Apple II systems as late as 1990.
1982: Joe Dellinger develops the Apple II virus at Texas A&M University, then codes the first antivirus program to stop its faster-than-expected spread.
1984: Fred Cohen writes the first scholarly paper naming computer viruses such, though Dellinger says he called his original experiment a virus.
1986: The first widespread MS-DOS virus, Brain, is released by Pakistani programmer brothers who want to see how many people are pirating their software. It’s harmless but infects every floppy diskette placed in any computer that touched the pirated software, spreading worldwide. The brothers now run an ISP in Lahore, Pakistan.
1987: The Jerusalem virus is the first widespread virus to delete files on purpose.
1988: Robert Morris Jr., son of one of the authors of Core War, releases a worm onto the nascent Internet. A bug in the worm causes it to crash about 10% of the computers that make up the `Net. Morris is later convicted of computer tampering for stealing passwords used to release the worm but goes on to become a professor at MIT.
1994: The Good Times virus hoax appears to America Online users. This is the first hoax to become a major global nuisance. No virus at the time can infect computers when users just open an e-mail, but that will become possible in four years.
1995: Concept, the first Microsoft Word macro virus, becomes widespread. Unlike pervious viruses, Concept attacks documents and can spread between computers running Windows, Windows NT & MacOS.
1998: CIH (a.k.a. Chernobyl), the first major virus to affect computer hardware, erases flash BIOS chips on some Windows-compatible machines, requiring replacement of the chips.
1999: The Melissa worm spreads faster than any virus in history by taking advantage of widespread Internet connectivity and nearly universal use of Microsoft products to e-mail itself to computers around the world. Author David Smith is later sentenced to 20 months in jail.
2000: The Love Bug worm girdles the globe, combining Melissa’s emailing features with a seductive subject line professing its love for the user. Filipino Love Bug author Onel de Guzman gets off scot-free, as his home country has inadequate computer-crime laws.
2001: The SirCam worm picks up infected users’ confidential files and sends them to random recipients, causing confusion and embarrassment.
2001: Designed to attack Web servers rather than personal computers, the Code Red worm defaces thousands of Web pages & attempts to launch a network-clogging attack on the Whitehouse.
2002: The most common virus at present time, the Klez worm sends confidential files through email like SirCam does, but trolls an infected user’s entire harddrive for both “to” & “from” e-mail addresses.