In marketing terminology, a killer application (commonly shortened to killer app) is any computer program that is so necessary or desirable that it proves the core value of some larger technology, such as computer hardware, gaming console, software, a programming language, software platform, or an operating system. In other words, consumers would buy the (usually expensive) hardware just to run that application. A killer app can substantially increase sales of the platform on which it runs.
One of the first examples of a killer application is generally agreed to be the VisiCalc spreadsheet on the Apple II platform. The machine was purchased in the thousands by finance workers on the strength of this program. Another is WordStar, the most popular word processor during much of the 1980s. The next example is another spreadsheet, Lotus 1-2-3. Sales of IBM's PC had been slow until 1-2-3 was made public, and then increased rapidly a few months after Lotus 1-2-3's release. The definition of "killer app" came up during Bill Gates's questioning in the United States v. Microsoft antitrust suit. Bill Gates had written an email in which he described Internet Explorer as a killer app. In the questioning, he said that the term meant "a popular application", and did not connote an application that would fuel sales of a larger product or one that would supplant its competition, as the Microsoft Computer Dictionary defined it.
Selected applications for computer systems 
Video games 
The term has also been applied to computer and video games that cause consumers to buy a particular video game console or gaming hardware over a competing one. Examples of a video game killer applications are:
- The first generally agreed example of a "killer app" in gaming is Space Invaders, released for arcades in 1978 and ported to the Atari VCS (Atari 2600) console in 1980, quadrupling sales of the then three-year-old Atari 2600 platform.
- Star Raiders, released in 1979 on cartridge for the Atari 8-bit computer, is considered to be an early gaming "killer app" for a computer platform.
- Donkey Kong was the killer app for the ColecoVision console in 1982.
- The video gaming website GameTrailers considers the Super Mario Bros. games to be the killer app for nearly all Nintendo home consoles, Tetris as the killer app for the Game Boy, Grand Theft Auto III for the PlayStation 2, Super Smash Bros. Melee for the GameCube, and Wii Sports for the Nintendo Wii.
- Sonic the Hedgehog, released in 1991, was hailed as a killer app as it revived sales of the (by then) three-year-old Sega Genesis / Mega Drive.
- Final Fantasy VII is considered a "killer app" that the original PlayStation had along with Metal Gear Solid. These were immensely popular exclusives that helped the console pull ahead of the Nintendo 64 for good. Earlier killer apps included Resident Evil, Tomb Raider, Gran Turismo and Crash Bandicoot.
- Pokémon Red and Blue would be classified a "killer app" for the seven-year-old Game Boy as a craze evolved around the series in the late 90s, and it was only available on that platform.
- Pokemon Gold and Silver were released at the height of the Pokemon craze alongside the Game Boy Color, and fueled the sales for the console all the way to the release of the Game Boy Advance two years later.
- GoldenEye 007 and The Legend of Zelda: Ocarina of Time are considered killer apps for the Nintendo 64.
- Quake is considered the killer app for hardware 3D accelerators in home computing.
- The Halo series is considered the killer app of the Xbox and Xbox 360.
See also 
- Scannell, Ed (February 20, 1989). "OS/2: Waiting for the Killer Applications". InfoWorld (Menlo Park, CA: InfoWorld Publications) 11 (8): pp 41–45. ISSN 0199-6649. Early use of the term "Killer Application".
- Kask, Alex (September 18, 1989). "Revolutionary Products Are Not in the Industry's Near Future". InfoWorld (Menlo Park, CA: InfoWorld Publications) 11 (38): p. 68. ISSN 0199-6649. Early use of the term "Killer App".
- D.J. Power, A Brief History of Spreadsheets, DSSResources.COM, v3.6, 8 August 2004
- "Killer Applications" (overview), Partha gawaargupta. Arizona State University in Tempe, AZ, May 2002, webpage: ASU-killer-app.
- Bergin, Thomas J. (Oct-Dec 2006). "The Origins of Word Processing Software for Personal Computers: 1976-1985". IEEE Annals of the History of Computing 28 (4): 32–47. doi:10.1109/MAHC.2006.76.
- Bourgeois, Derek (2001-11-01). "Score yourself an orchestra". The Guardian (Guardian Media Group). Retrieved 2011-05-10. "Many composers bought an Archimedes simply to have access to the program."
- "The Definitive Space Invaders". Retro Gamer (Imagine Publishing) (41): 24–33. September 2007. Retrieved 2011-04-20.
- Craig Glenday, ed (2008-03-11). "Hardware History II". Guinness World Records Gamer's Edition 2008. Guinness World Records. Guinness. p. 27. ISBN 978-1-904994-21-3.