Note: I've also written about this on my site with more notes and context: https://jaytaylor.com/writeups/2018/why-referrer-header-empty-nowadays.html https://

Note: I've also written about this on my site with more notes and context: https://jaytaylor.com/writeups/2018/why-referrer-header-empty-nowadays.html https://jaytaylor.com/writeups/2018/why-referrer-header-empt... -- Short version: These days the referrer header rarely makes it through for 2 main classes of reasons [0]. 1. Requests transiting across HTTP <-> HTTPS boundaries do not include the referrer header. 2. The referrer header is frequently disabled by sites (especially search engines and high-traffic sites) through the use a special HTML header meta control tag [1]: <meta name="referrer" content="no-referrer" /> Worry not, though. When client-side Javascript is enabled, ga.js still sends enough information that Google can reconstruct most of everyone's browsing sessions on their backend. Now Google (and only Google) really has all your / our data (generally speaking). :-\ [1] https://stackoverflow.com/questions/6880659/in-what-cases-will-http-referer-be-empty https://stackoverflow.com/questions/6880659/in-what-cases-wi... [0] https://stackoverflow.com/questions/6817595/remove-http-referer https://stackoverflow.com/questions/6817595/remove-http-refe...