Microsoft is the software industry's nonplus-ultra, with a revenue of $103.3 billion. Co-founders Paul Allen and Bill Gates established the firm in 1975. The American software behemoth, founded in Albuquerque, New Mexico. Its headquarter is in Redmond, Washington, USA. Microsoft provides a wide range of applications for a variety of reasons. Yet, its most well-known and successful franchise product is Windows. It is the operating system software. It almost runs on about a billion PCs worldwide. It is by far the most used operating system on the planet.