A specialization of ComputerProgram_CW. Each instance of OperatingSystem is a program that provides an environment in which a user can execute instances of ApplicationProgram (q.v.) on the hardware of a computer. That is, running copies of instances of OperatingSystem serve as systems that look for and understand user commands, regulate how system resources are used by application programs, handle the internal operations of computers, and so on. Note that OperatingSystem is disjoint with ApplicationProgram and OperatingSystemKernel (q.v.), and that together these three collections partition ComputerProgram_CW.