Link to a specific part of the document, the headings (H1, H2, H3 ...) to be exact, and thus have a visible index or, at least, have the direct link in that specific part of the document.

It is very convenient to be able to have a subtitle link to refer to the part of the document that interests you.

https://developer.mozilla.org/en-US/docs/Web/HTML/Element/a#linking_to_an_element_on_the_same_page