I do not get the internal links lesson. Can anyone try to explain please?
Links can point either to external resource or to internal section (or any other element) referring it by id:
<div id="top-of-the-page"> <!-- tons of the content --> <a href="#top-of-the-page">Get back to the top</a>
It’s normally used if page has any sort of Table of Contents or in “jumping/skipping” to the next section or top scenarios.