The primary function of a network operating system (NOS) is to manage network resources and facilitate communication between multiple devices on a network. NOS provides essential services such as file sharing, printer access, and user management, enabling efficient collaboration among users. It allows for centralized administration of resources and security policies, ensuring that devices and users can connect seamlessly. Examples of NOS include Windows Server and Unix/Linux-based systems. A well-implemented NOS enhances network efficiency and reliability.