The purpose of a network protocol is to establish rules for communication between devices over a network. Protocols dictate how data is formatted, transmitted, and received, ensuring that devices can understand and process the information exchanged. Examples include TCP/IP for data transmission, HTTP for web browsing, and FTP for file transfers. By standardizing these processes, network protocols enable diverse devices and systems to connect, communicate, and work together efficiently. Without these protocols, interoperability would be compromised, leading to connectivity issues and confusion in data transmission.