Yes, this simple concept of a user can quickly transcend into a complex idea involving cookies, devices, browsers and logins. For GA, a user is identified by cookies stored on their device, and the cookies are tied to specific browsers used by the visitor. So, if I visit care.com using the Chrome web browser on my laptop, GA will count me as a single user. However, if I revisit the site using an iPhone’s Safari web browser, I’ll be counted again. In today’s multidevice usage, this is a common scenario that one must account for while analyzing data. If your site has a login functionality, multiple sessions across devices and/or browsers can be grouped together through the User-ID feature provided by GA. Talk to your analytics team about this option.
While looking at data over multiple days, you’ll notice the sum of individual days does not match the overall number reported by Google. That’s because of the uniqueness aspect of this metric. Users viewing your site twice over two different days in a week will show up only once in the total reported by GA. When I visit wikipedia.com on every day of the week, it counts me as a single visitor for each day. But in a weekly report, I’ll show up only once, not seven times, as that would be a different interpretation of reality.
Lastly, as long as I’m using the same device and browser, GA will identify me as the same user irrespective of the channel I’m using. I can click on a link in the newsletter or a social post and GA will seamlessly weave my journey together as one user with multiple traffic sources and pageviews.