Complicated concepts are often best explained in metaphor, so I’m taking a shot here at explaining Hypertext Transfer Protocol through a childhood experience.
You know that ‘HTTP’ that usually starts off urls? It represents one of many protocols that servers and clients (that’s your machine accessing the web right now) use to talk to each other. The HTTP tells both machines what to look for when parsing the information, and a developer with knowledge of these protocols will also know what to look for and can use the information being passed back and forth.
A protocol isn’t a language, it’s simply an agreed-upon structure for conveying information. For example, when my friend Oriana and I were bored in 9th grade history class, we would pass notes back and forth that obeyed ‘Galen and Oriana’s Disgruntled Onomatopoeia Protocol.’ It looked like this: