The :any-link pseudo-class in CSS provides a method for selecting elements that are the source anchor of a hyperlink.

If the term source anchor lost you, that's a fancy name for the href attribute on the HTML elements <a></a>, <link /> and <area />. (Why you would need to target an <area /> or <link /> in CSS is beyond me, but hey.) The HTML spec has a whole lot more information on that.

An element that accepts and contains a href attribute is a hyperlink and will be selected with :any-link. This becomes a handy way of selecting all link-based HTML elements that might otherwise appear unrelated and without touching the markup. Perhaps it exists because you might think :link would select all links, but it misses :visited, so this wraps them all up together.

Functionally, it's just like the attribute selector [href].