A relative recently lost her Android device, and ask me for assistance. Since reporting it to the authorities in our case NTC takes a lot of time and effort which most working class people don’t have; we resorted to Google!
Since every android device is linked to your personal Google account you can access your devices via the Android Device Manager. Here you can opt to locate, lock or erase your phone if lost.
It’s not a bullet proof solution since your device has to be connected to the internet for it to receive the request from Google. I’m sure shady people have found ways to get around this problem but at the very least you get to make it harder to the person who stole your phone to sell or use it. You can also erase and sensitive data you may have on your device, some sexy videos perhaps?