Cross-Domain Measurement

Cross-domain measurement is an analytics configuration intended to recognize a user's activity as one journey when it moves between designated websites on different domains. It can matter when a service business sends visitors from its main site to a separately hosted booking or checkout service. Without appropriate setup, analytics may assign separate users or sessions or misattribute traffic when someone crosses domains. In GA4, participating domains need compatible tagging in the same web data stream, and the links or forms between them must allow the linker parameter (_gl) to pass through without being removed by redirects. For example, a booking provider must permit the necessary tags and URL handling; merely adding its domain to a list will not make unsupported third-party platforms work. Cross-domain measurement is different from tracking ordinary pages on one domain. It does not override consent requirements or guarantee that every visit can be linked to a single person.