Microsoft Windows, commonly referred to as Windows, is a family of proprietary graphical operating systems developed by Microsoft, which includes various products for different markets and industries that use a similar user interface and feature set. The original version of Windows was a graphical environment running on top of MS-DOS, although later versions increasingly took on the characteristics of a full operating system. Since Windows XP, all desktop versions of Windows use the portable NT hybrid kernel that does not rely on MS-DOS.