The primary function of an operating system (OS) is to act as an intermediary between computer hardware and users. It manages hardware resources like CPU, memory, and storage, enabling efficient utilization. The OS provides a user interface, allowing users to execute commands and run applications. Furthermore, it oversees file management, system security, and task scheduling, ensuring multiple applications can run concurrently without conflict. By handling these core functionalities, the operating system ensures that users can effectively interact with and maximize the capabilities of their machines.