Thanks for the downvote, but you're wrong.
> explicitly and implicitly describe the layout of an HTML document.
No, this doesn't happen.
> In fact, "HTML" itself is an acronym (HyperText Markup Language)
Duh.
> in which the "Markup" describes the function of HTML to "mark up" text in a similar way that editors once did in the print industry, describing which parts of the text should be bold, italicized, etc. or divided up and in what way.
Which has fuck-all to do with the layout.
I didn't downvote you, and I'm not wrong. And all you're responding with is invective. Go touch grass and read a book. Bye.
> And all you're responding with is invective.
This statement is mendacious, at best. I have explained that HTML has fuck-all to do with layout. I can explain it to you, but I can't understand it for you.
Here, check out what the W3C has to say about it:
> Because HTML conveys meaning, rather than presentation, the same page can also be used by a small browser on a mobile phone, without any change to the page. ... But it goes further than just differences in screen size: the same page could equally be used by a blind user using a browser based around speech synthesis, which instead of displaying the page on a screen, reads the page to the user, e.g. using headphones. Instead of large text for the headings, the speech browser might use a different volume or a slower voice.
(Emphasis in the original.)
https://html.spec.whatwg.org/multipage/dom.html#semantics-2
Also, check out the ACID series of specifications which require and always use CSS, because otherwise, there is no mandate on how a browser should display stuff.