Referrer Policy is the system that browsers and websites use to inform destination websites about the source website whence a resource request is coming.  For example, if you visit a website (say https://fake-cat-site.org), and it includes an image requests for a cat (say, https://example.org/cat.png), referrer policy instructs your browser to tell example.org that the request for the image came from fake-cat-site.org.  Similarly, when you click on a link (say, from a search results page), referrer policy typically instructs your browser to tell the site you're visiting that you came from the search results page.[^6]