Google Analytics is a web analysis service provided by Google that collects information about you and how you use sites like

This information allows us to better understand who you are and what you’re looking for so that we can provide increasingly more relevant and meaningful content.

Google Analytics record things like how you got here, how long you stay, what you click on and various other pieces of demographic and usage data.

All of this falls within Google Analytics Terms of Service and you can opt out of tracking on here.