Referrals are the portion of the traffic that reaches your website via a hyperlink from a different domain.
Google Analytics automatically recognizes where traffic is referred from before arriving on your site, and displays the domain names of these sites as the referral source in your reports.
However, sometimes a session is incorrectly marked as a referral, when it is really part of the same user journey.
To make sure you don't break the user session with an incorrect referral, you can create a set of conditions that identify the domains whose traffic you don't want to include as referrals.
Google Analytics previously called this 'referral exclusion' but now calls the feature 'unwanted referrals'.
Here are some scenarios in which you would not want to identify traffic from a domain as referrals:
We don't recommend excluding your own domain, as this can mark self-referrals which are generally caused by missing tracking
Navigate to the Reports tab on the left side
Go to the Acquisition > Traffic Acquisition report
Scroll down until you see the search box and type referral
Click on "Session default channel group" and select source/medium
You will now be able to see referral traffic in GA4: