The primary utility of an operating system (OS) is to manage computer hardware and software resources, providing a user interface for interaction. The OS acts as an intermediary between applications and hardware, facilitating functions such as process management, memory allocation, and device control. Additionally, it provides essential services like file management, security features, and user authentication. Examples of popular operating systems include Windows, macOS, and Linux, each serving unique user needs and computing environments while ensuring system stability and efficiency.