Protocols are used in networking to provide a way for devices to share and understand information sent across the network.
Protocols occur in human life and make life a little more orderly but without laws. Protocol says that we normally walk on the right side of the hall. It is not a rule but as long as most people do it, crowds more easily manage the hall. Protocol says that we as Americans do not bow or curtsey for the queen of England as British subjects do, however protocol does say that we do not touch her and particularly not hug her.
There are tons of protocols used on networks. Many of them are used to allow devices to communicate with each other. For instance DHCP is a protocol that assigns addresses to devices on the network.
The protocol says how the messages will look and also the types of information in the message. If both devices use the same protocol then w\hen one device sends a message to another device, the receiving device will understand and use the message.
We as humans use a number of protocols to get and send information. A very common one used by humans is http which you see listed on addresses for the Internet sometimes. HTTP allows us to send requests to web page servers and them to send the web pages back to us so we get the right information. SMTP is a protocol used to send email. There are literally thousands of protocols and we know most by their acronyms. For instance HTTP is HyperText Transfer Protocol and SMTP is Simple Mail Transfer Protocol.