The specific format of a request (and the resulting response) is called the protocol .
What exactly protocol is in binary level ?
I could imagine like this : a computer(server) is standing for binary pulses in it’s entry wire and a process inside computing device is capturing pulses and an specific pulse mean protocol A another sequence of pulses over internet wire mean protocol B ?? protocol in software level ?
Protocol in physical layer is understandable and is type of wires strictly connected to each other .