Definition of an Operating System

Several More Definitions of an OS:

• "A program that manages a computer’s resources, especially the allocation of those resources among other programs." — Encyclopedia Britannica
• "An interface between a computer user and computer hardware." — Tutorials Point
• "Software that controls the operation of a computer and directs the processing of programs." — Merriam-Webster
• Another idea: A program that operates from a device's launch to its shutdown.