Microsoft (MS) Corporation personal computer (PC) operating system (OS). Microsoft introduced this OS in 1985 and it continues to be widely used despite competition from Apple’s Macintosh OS. As with other operating systems, Windows provides a computer system user-friendly interface that provides a graphical display. It also organizes information for easy access and retrieval. The OS uses icons and tools to simplify complex operations executed by the PCs. Industry surveys state that the Windows operating system is in 90% of the personal computers world-wide.