Microsoft Windows is a series of software operating systems and graphical user interfaces produced by Microsoft. The most recent client version of Windows is Windows Vista, the most common being Windows XP.

Windows dominates in the desktop and personal computer markets with about 90% of the desktop market share. Windows differ from others OS in philosophy, cost, ease of use, versatility, and stability, with each seeking to improve in their perceived weak areas.

Windows operating systems compete for user-base in the personal computer market as well as the server market, and are used in government offices, schools, business offices, homes, intranet and internet servers, supercomputers, and embedded systems.