Google rolled out a new feature called Your Timeline last night. They say that it lets you "view the places you've been on a given day, month or year." I'm well aware that Google and many other services use location tracking to target advertising, help you recover a lost device, security settings, etc. But, this one feels even more intrusive and a little bit creepy to me.
It's now supposedly "private and only visible to you". If, like me, you would like to prevent Google from having this level of access to where you've been, you need to turn your location history off. You can find instructions to turn off and even delete your location history here.