This wired article is a long read but I promise you its worth it.
<tl/dr>
Don't allow your #smartphone to access your #location. Don't ever share location data with any app.
Seriously.
"If you ever granted an app permission to know where you are 24/7, there is a good chance a detailed log of your precise movement patterns has been vacuumed up and saved in some data bank somewhere that tens of thousands of total strangers have access to. That includes intelligence agencies. It includes foreign governments. It includes private investigators. It even includes nosy journalists."
