If html is not a programming language, what is it

Answer 1

It is a markup language.
https://www.sololearn.com/learn/HTML/1021/

Answer 2

HTML, Hyper Text Markup Language, is a markup language. The difference between a markup language and a programming language relies mostly on the capabilities and functionalities of the two. Programming languages generally are given a set of instructions written in code for it to follow, resulting in some sort of output. It uses functions, variables, classes (sometimes), and other things that markup languages would not generally use. A markup language is a language that uses tags to hold information in tags in a way that both humans and computers can easily read it. HTML is a markup language because it uses tags to hold information, which is then displayed in the form of a website.

Answer 3

There is answer:
https://softwareengineering.stackexchange.com/questions/241104/programming-language-vs-markup-language-vs-scripting-language