A network operating system (NOS) is software that manages network resources and allows multiple computers to communicate and share data. It provides essential services such as file sharing, printer access, and user management, enabling users to collaborate effectively within a networked environment. Common examples of NOS include Windows Server, Linux, and Novell NetWare. NOS is designed to support various network protocols, ensuring compatibility between different devices and systems. It also enhances security by managing user permissions and access controls, protecting sensitive information from unauthorized access. Overall, a network operating system is crucial for maintaining efficient and secure network operations.