Each visitor to a website is identified by Google Analytics with a unique ID. The first time a user logs into a website from a new device or browser, they are called a New User. Each new ID registered by Google Analytics is considered a new user. Because this ID information is stored in users' browsers, and therefore on their devices, they are considered a new user with a new ID if they visit the same website using a different device or browser. When a user revisits a website using the same browser, they are considered a returning user, not a new user.
