Yep, you called it protocol which I did gather is the correct term. When I learn new concepts, especially ones as abstract as this conversation is turning out to be filled with, it helps me to rephrase it in more colloquial terms such as "language" or maybe "encryption" - I do this when I teach too, and I often get comments from students that it helps their understanding of the material.

But of course every model has flaws, and recognizing the flaws of your analogy is just as crucial to good understanding in the end as picking a decent analogy was in the first place. I'm thinking that calling a protocol a "language" may be implying more complexity to protocols than they really have; perhaps comparing different protocols to different encryption schemes would be more analogous?

But I hadn't realized that there were different protocols in the first place - I thought everything just used FTP. I even thought SSH/SFTP and HTML were subsets of FTP.