Page referrer is one of the URL dimensions that deserves a special mention.

Technically it gives the previous page that the user was on before they landed on the current page. However, this comes with a lot of buts:

• A website gets to choose whether they pass the referrer field. They can turn this off meaning if someone clicks from such a website to yours, the referrer will be blank. This will also place the traffic in the direct category (unless you’ve managed to UTM tag the link but that won’t happen with unsolicited links).
• Most browsers have set a default referrer policy to only pass the domain name that the user came from, not the full URL. For example, if someone clicks from Facebook to your website, all GA4 will see is https://www.facebook.com/, not the full page. This is to improve privacy and security and while it’s possible for websites to override this, most don’t.
• If the user is already on your website, this field will show the previous page they were on, which is very good for path analysis (and is in fact what GA4 uses for page pathing reports).
• Unless your website is an SPA (single-page application). Then, depending on how it’s implemented, the referrer will often point to the first page that the user landed on (ie. when they did a full request of your website) and ignore any subsequent soft page reloads. GA4 tries to cope with this inconsistency automatically but it often doesn’t work. What we’ve found is that it may be best to use Google Tag Manager to set the page_referrer parameter manually for such cases.

When the referrer dimension used to pass the full URL that someone clicked to your website (we’re talking before 2020 while GA was still Universal Analytics), this was a useful dimension to work out which specific pages from large websites are giving you traffic. This isn’t a real use case these days as it doesn’t provide any more info than the source/medium dimensions. It still remains a good tool for user path analysis inside your website, but then you should check that it’s correct for your website (especially if it’s an SPA). You can do this in DebugView or just by navigating to a 2nd page in the browser, going to the browser console and typing document.referrer to see what comes up.

There are also 2 types of referrals you’d usually want to exclude in your GA4 settings:

• Referrals from one of your own websites (ie. one of the websites you are tracking in this very GA4 property).
• Referrals where the user has just returned to the website from a booking engine or payment processor (eg. paypal.com) where this means they have just converted.

Excluding a referral does NOT remove the data from your reports. It just stops the session from being attributed to the referrer you excluded. Usually what will happen is that the session will be attributed to the traffic source. Without this, you might have paypal.com showing up on your reports as your top ecommerce conversion source, whereas what you’d want are the sources people use to actually click through to your website.