Modern communications mean most individuals today walk around with a beacon that transmits their location. Mobile phones register to a nearby tower as the owner moves through space and the phone company can collect that data in real time or retrospectively to physically place the phone with varying degrees of accuracy. Companies can also determine the owner of every handset within range of a particular tower. GPS enabled phones enable far more precise location placement. Many cars now have GPS devices installed some of which transmit the vehicle’s location to a centralized service. As the devices get cheaper and smaller law enforcement agencies can more easily attach GPS trackers to cars and individuals enabling precise round-the-clock surveillance without ever leaving the precinct. Location-based services including maps of nearby restaurants friend finders and other social networks collect location data as part of providing the service or for contextual advertising.