Bluetooth implementation on the micro:bit
The micro:bit uses a Nordic nRF51822 processor, which has an on board Bluetooth transceiver. Combined with a PCB trace aerial and other minor components, and the Nordic S100 SoftDevice Bluetooth stack, this gives the micro:bit a certified and credible Bluetooth capability.
With Bluetooth, you can connect to other devices and send and receive data. Bluetooth software features appear in many of the languages, including Makecode and mbed C++, as well as their being micro:bit compatible applications for Android and iOS devices (phones and tablets).
The Nordic nRF51 also has a number of non-bluetooth proprietary modes of operation, one of which is called Gazell. The Gazell protocol only works between micro:bits (or other Nordic enabled devices), and this surfaces as the ‘radio’ feature in Makecode and MicroPython, as well as mbed C++.
micro:bit Bluetooth Features
Bluetooth features available on the micro:bit are defined in a Bluetooth profile. The micro:bit supports one profile, which was custom developed for the micro:bit. Read about it here