Windows NT now refers to a family of Microsoft operating systems, all based on the original Windows NT released in 1993. All Windows operating systems since (XP, Vista, 7, etc.) are based on the NT kernel.

The Windows NT kernel is considered a hybrid kernel, and is also sometimes called a macrokernel. Although most system components run in the same address space, some subsystems run as user-mode server processes and many of the design objectives are the same as Mach.