Google uses first-party data for user preferences and authentication and third-party cookies for advertising.

 Understanding the cookies used by Google Analytics and the critical issues surrounding the domain to which those cookies are written and read is paramount to the accuracy and reliability of your Google Analytics data.

The number one problem I consult with clients on solving relates to cookie domain issues. It most commonly manifests in the form of “self-referrals”, i.e. you see your own domain name listed in the “Referring Sites” report. That is because of a cookie domain problem.

Other issues of high bounce rates, inflated visitor and visit numbers, and deflated time on site and page/visit metrics also relate to cookie domain problems.

Yes, Google Analytics is “available, easy, and free” – but it’s not really that “easy” to set up properly. 

How does Google Analytics identify users that it’s tracking?

Just like most tracking technologies out there it uses cookies.