I know that Google is collecting much information with Analytics. Analytics uses first-party cookies, so Google shouldn't be able to recognize a person on different websites. How is the Cross-Domain-Tracking working?
Let's say a person visits website A with GA and Google tracks it an stores the information on a server (Website sets first-party-cookie)
Now the person visits website B with GA and Google tracks it again (Website B can't read the first-party-cookie of website A, Website B sets another first-party-cookie)
Now the person visits website C with AdSense. How does Google know which advertisment they should show? Without third-party-cookies they can't know that the visitor was on the websites A and B before.