Bluetooth is a small-scale wireless interface. 2.4 Gigahergee waves transfer via Bluetooth data. It works about 10 meters in distance and works at 1 Mbit / s.
Many devices work in the Bluetooth mobile interface.
You can hear the sound without Bluetooth headphones without them.
The Bluetooth keyboard mouse has been used long ago.
Remotely locking via Bluetooth lock.
Different devices without hand watches are now using Bluetooth.