Cross domain traffic is one of the overlooked features in Universal Analytics. It gets a bit frustrating when people have multiple domains. It is not actually the most straightforward process in Universal Apps. However, in GA4 cross domain tracking can be found under More Tagging Settings. To set up cross domain tracking in GA4, go to Admin > Data Stream > More Tagging Settings > Configure Your Domains. You can easily define parameters from there and place the tag on websites. And that’s it. You have cross domain tracking. Read More