A protocol is like a language spoken by a computer.
But think of humans first. One of the ways we communicate is through speech. But we’re not just making random sounds. Those sounds are in a pattern, this pattern is a language, and there are many different languages.
A device on the network also needs to communicate with other devices. But it can’t send random 1’s and 0’s. The signals it sends need to be organised in a way that the receiver can understand.
And that’s what a protocol is. A set of rules that define how information is sent, received, and interpreted.
There are hundreds of different protocols, all with different purposes. For example, you may have noticed that some websites start with http or https. This is the Hypertext Transfer Protocol. Web browsers use this to download and display a web page.
Quite often, several protocols work together to achieve different parts of a larger task.