Bluetooth
Bluetooth is a short-range wireless technology, about 10 metres, that lets two devices exchange data without cables.
It runs on the 2.4 GHz band and is designed for close, low-power connections: headphones, watches, speakers or the car. Its Bluetooth Low Energy (BLE) variant uses so little power that small beacons can run for months on a single battery.
In marketing, those beacons show that a phone has been near a specific spot -a shop entrance, a cinema screen, a festival stage- and so measure physical visits. Like any data of this kind, using it for advertising requires user consent and anonymous, aggregated processing.
