Meaning – The term protocol, refers to the meanings of, and the sequencing rules for, requests and responses used for managing a network, transferring data, and synchronizing the states of network components.
These rules include what type of data may be transmitted, what commands are used to send and receive data, and how data transfers are confirmed.
You can assume the protocol to be similar to a language. Each language has its own rules and vocabulary. If two people share the same language, they can communicate effectively. Similarly, if two hardware devices support the same protocol, they can communicate with each other, regardless of the manufacturer or type of device.
Example of usage – “Link-layer protocols establish communication between devices at a hardware level. In order to transmit data from one device to another, each device’s hardware must support the same link-layer protocol.”