Programming Language vs. Markup Language
By the way, saying HTML is a programming language is not 100% accurate. More precisely, HTML is a so called markup language. As explained in the introduction you define the type and meaning of content. So the "M" for "Markup" in HTML basically means to mark up the content as a specific type. To gain a better understanding what a markup language is, you can take a look at the comparison between the the popular language Markdown and HTML.
In my opinion, it is not important to differentiate between markup and programming language. Many people call HTML a "programming language" or use the verb "programming" to describe writing HTML code. Its mostly just elitists being pedantic about exact word choices. Oftentimes such people are application developers belittling and ridiculing HTML developers. Talking down to others is probably just a way to make the person feel more important or as something better at doing "real" programming, such as modeling the flow of data or constructing application logic and behavior.
If you understand the rough distinction between markup and programming language, you don't need to read any further. You can still continue with What is a programming language? if you want to gain a better understanding about what a programming language is.
The section Markdown vs. HTML makes more clear what a markdown language is by comparing HTML to the popular language Markdown.
Programmer and Donkey Joke:
- "Hello Mr Programmer", the donkey said, "how are you?".
- "mighty fine, thank you donkey", the HTML dev replied.
- Immediately the donkey started crying.
- "What's the matter little friend?" the HTML dev asked.
- "I called you a programmer, at least you could call me horse" the donkey bawled.
Violence is never the answer:
Two boys fighting. Elderly guy saying: "violence is never the answer". Boy in red shirt saying "HTML is a programming language". Elderly guy twitching for a moment and then punching the boy. I recreated this meme variation that I found on reddit. The original comic strip is by the artist Pandyland.
The comic depicts how some conversations take place. Hopefully, you don't start a fight over slightly imprecise choice of words.