An operating system (OS) is system software that manages computer hardware and software resources, and provides common services for computer programs. It acts as an interface between the user and the computer hardware, and controls the execution of all kinds of programs. The OS manages all the resources of the computer, including memory, processors, storage, and networking. It also provides a comprehensive platform that identifies, configures, and manages a range of hardware.

The OS performs several functions, including:

• Memory management: The OS manages the computers memory and processes.
• Process management: The OS manages all of the other application programs in a computer.
• File management: The OS manages the storage of files on the computer.
• Device management: The OS identifies and configures physical and logical devices for service and typically records them in a standardized structure.

Examples of operating systems include Microsoft Windows, macOS, and Linux. Without an operating system, every application would need to include its own user interface, as well as the comprehensive code needed to handle all low-level functionality of the underlying computer, such as disk storage, network interfaces, and so on.