Bluetooth is an open standard for wireless connections. It’s special designed for short range communication between devices.
Bluetooth works in the 2,45 GHz spectrum and has a range between 1 till 10 meters. The throughput is 1 Mbps and can communicate with 8 active devices and connect with 127 devices at once.
The big advantage of Bluetooth is it’s low consumption of current. 30 µA in Hold mode and 8-30 mA for a active connection.