What is the purpose of a network protocol?

The purpose of a network protocol is to establish rules for data communication between devices. This involves defining how data is formatted, transmitted, and processed by the sending and receiving devices, ensuring that they can understand each other. Protocols create a framework for communication, detailing aspects such as error handling, data compression, and how to establish and terminate connections. Without these standardized rules, devices from various manufacturers and running different operating systems would struggle to communicate effectively, leading to inefficiencies and errors.

While limiting bandwidth usage, creating secure connections, and automatically assigning IP addresses are important functions within networking, they do not encompass the broader, foundational purpose of protocols, which is primarily to facilitate reliable and coherent exchange of information.