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. NOS can be installed on servers and client machines, facilitating centralized control over network operations. Common examples of Network Operating Systems include Microsoft Windows Server, Linux, and Novell NetWare. These systems ensure security, reliability, and efficient resource allocation, making them vital for businesses and organizations that rely on interconnected devices.