This really should not come as a surprise. BGR:
Google’s mobile Maps apps for Android and the iPhone track everywhere you go. Every single day. All of the time… Even when the app is closed, your every move is tracked and stored on Google’s servers. Every day, every week, every year.
What does Google do with all the data?
This data is put to use in a number of ways. It helps Google better tailor its services to each individual user, and it also obviously helps Google build a more accurate advertising profile of each user.
Can you opt out of the collection process? Yes.