The function of an operating system (OS) is to manage computer hardware and software resources while providing a stable environment for applications to run. It acts as an interface between users and the computer hardware, enabling interaction through a graphical user interface (GUI) or command-line interface (CLI). The OS handles various tasks such as process management, memory management, file system operations, and device management. Essential examples of operating systems include Windows, macOS, and various distributions of Linux, each designed to optimize user experiences and system performance.