Anchor text
Anchor text is the visible, clickable text of a hyperlink. Search engines use it as a description of the linked page, which is why descriptive anchor text helps both users and ranking, and why generic anchors like 'click here' throw that signal away.
When a page links out, the words in the link describe the destination. Search engines have used this since the earliest days: it is a description of a page written by someone other than that page’s owner, which makes it harder to manipulate than the page’s own title.
This applies to internal links as much as external ones, and internal anchor text is entirely within your control. A site that links to its crawling guide with the words “crawling guide” is stating what that page is about, on every page that links to it. A site that links with “read more” states nothing.
Two cautions. Anchor text that is identical across hundreds of external links, especially exact-match commercial phrases, is a recognised manipulation pattern and is discounted. And anchor text describes the destination, so it should describe what the reader will find there, not what you want the page to rank for. Where those differ, you have a content problem rather than a link problem.