Operating system An operating system ( OS ) is system software that manages computer hardware and software resources and provides common services for computer programs . All computer programs, excluding firmware , require an operating system to function. Time-sharing operating systems schedule tasks for efficient use of the system and may also include accounting software for cost allocation of processor time , mass storage , printing , and other resources. For hardware functions such as input and output and memory allocation , the operating system acts as an intermediary between programs and the computer hardware, [1] [2] although the application code is usually executed directly by the hardware and frequently makes sys...