A protocol is a set of basic rules that allow electronic devices to communicate with each other. These instructions include the types of data that can be sent, the commands used to send and receive data, and how to validate data transmissions.
It is a set of rules that communicate over the internet with other device(s). It is a set of mutually accepted and implemented rules at both ends of the communications channel for the proper exchange of data.
There are three types of Protocols in IoT