This is less of a TIL and more of a “I am writing this down in the hope that I don’t need to Google it again when I next run into it” (as are a lot of these TILS).
According to people on the internet who know more than me, the proper hierarchy for semantic HTML tags is as follows.
<html>
<body>
<header>Header Stuff</header>
<main>
Main is a per page component that should contain the main (get it...)
content of the page but not the stuff that is repeated on every page e.g.
Nav and Footer
</main>
<footer>Footer stuff</footer>
</body>
</html>