Protocol refers to a set of rules or guidelines that govern the communication and interaction between different devices or systems in a network. It ensures that data is transmitted and received correctly and consistently, enabling devices to communicate effectively with each other. Protocols can vary depending on the type of network and the level of communication required, such as internet protocol (IP) for routing data on the internet, transmission control protocol (TCP) for reliable communication between devices, and hypertext transfer protocol (HTTP) for transmitting web pages. Protocols play a crucial role in ensuring the smooth and efficient operation of networks and systems.