<mark> is interesting because it suggests a 2-way authoring web that was originally envisioned, but failed to come to fruition, with usage notes like, Think of this like using a highlighter pen in a book to mark passages that you find of interest. The yellow here is the default style in all major browsers.
John Doe’s Page | A simple way to make HTML websites
This website is a single HTML file. It simply uses the #anchor suffix (from 1992) and the :target CSS selector to show and hide pages/content.
This setup is databaseless, javascriptless, and buildshit-free, so you can edit your website with a text editor and upload it somewhere like a normal person.