What does Google Analytics use to differentiate new and returning users?

Google Analytics differentiates new and returning users primarily through the use of a browser cookie. When a user first visits a website that is being tracked by Google Analytics, a cookie is placed in the user's web browser. This cookie stores a unique identifier that allows Google Analytics to recognize the user on subsequent visits.

When the user returns to the site in the future, Google Analytics checks the cookie to determine if it has been seen before. If the cookie is present, the user is classified as a returning user; if not, they are classified as a new user. This method relies on the cookie data to accurately attribute user sessions and help marketers understand user engagement and behavior over time.

Other options such as artificial intelligence, a randomly-assigned unique identifier, or a sequential unique identifier do not directly serve the purpose of distinguishing between new and returning users in the context of Google Analytics. The cookie-based identification is a fundamental mechanism that provides straightforward tracking of user sessions across visits.