Bluetooth tethering is one of the tethering methods which is used to share your mobile's data connection with other devices via Bluetooth.
It uses less battery power while compared with WiFi tethering. However, it is the slowest in terms of speed while comparing with WiFi tethering and USB tethering.
The main drawback here is that you can share the internet with only one device at a time.
For Bluetooth tethering, no software or peripherals are required. But, there are two important things to ensure before doing it.