This website shows your HTTP referer. As simple as that. Your referer is the page you're coming from. Why would you want to know your referer?
Request Headers in the HTTP protocol May 03, 1994 HTML DOM referrer Property - W3Schools Definition and Usage The referrer property returns the URL of the document that loaded the current document. Security/Referrer - MozillaWiki Apr 12, 2018
As stated by others very well, HTTP_REFERER is set by the local machine of the user, specifically the browser, which means it's not reliable for security. However, this still is entirely the way in which Google Analytics monitors where you're getting your visitors from, so, it …
Referer Control - Chrome Web Store Referer Control grants full control over the HTTP Referer. You can forge any referrer you want, both globally or on a per-site basis. Alternatively you can choose to disable the Referer completely. wp_get_referer() | Function | WordPress Developer Resources Top ↑ More Information # More Information. HTTP referer is a server variable. ‘referer’ is deliberately misspelled.. If page “refered” (form posted) to
Referer header: privacy and security concerns - Web
The ngx_http_referer_module module is used to block access to a site for requests with invalid values in the “Referer” header field. It should be kept in mind that fabricating a request with an appropriate “Referer” field value is quite easy, and so the intended purpose of this module is not to block such requests thoroughly but to block the mass flow of requests sent by regular browsers.