HTML:
“HTML” stands for “Hypertext Markup Language”.
Hypertext:
Hypertext is basically TEXT with LINKS in it to other (pages of) text. Another word for such a LINK is “hyperlink” although these days it is mostly just abbreviated to “link”.
So the word “hypertext” was created to describe “text that included hyperlinks”.
Another place you may come across “hyper” is in the related word “hyperspace”, an early term for the internet (basically a “space” filled with “hypertext links”).
These days however, about the only place you’ll find the word “hypertext” anymore is actually in this term “HTML”, it is otherwise rarely used. “Hyperspace”, is also a word that, while still used occasionally, is pretty rare – we now just use “internet” etc.
So the most common usage for hypertext these days is of course web pages. Most web pages use (hyper)links. And in most cases now, if someone says “an HTML page” they mean a web page. This is the foundation of the “World Wide Web” (www) which most people know/ think of as the internet (which is not technically 100% correct but that’s a story for another day).
Hyperlink example: This link goes to Google. That is a hyperlink.
Markup:
Markup is defining the formatting and layout of text:
It is what printers of books and such have done for all the years since the printing press – to take the context (the actual text) and then literally mark on it formatting requirements – “bold letter here, new paragraph here, put this text in a box over here, use a different font here …”. On a web page you do the same thing, using various codes and symbols to tell the computer how to display your text. The writing or code you use to designate “what formatting where” is is called “markup”.
Language:
Language is generally a computer programming term for the structure, grammar, words etc used to program a computer to do something:
There are many (many!!!) languages used for programming computers. Oddly enough HTML is NOT really a programming language! It is a “markup language” – and even that seems a misuse of the word “language”, it is a layout, formatting, design sheet really. This is not considered programming as there is really no extra calculation or variation or computation or user input required – the markup instructions say display something in a certain way, and that’s the way it is displayed. But HTML is called HTML for better or worse, so there you go.