Bluetooth gives a short-range wireless capability so that two devices can communicate with each other and it operates on 2.4 GHz ISM. This technology is based on IEEE 802.15.1 standard. Bluetooth is preferable over IR because it is not easy to decode.
Various version and their specification a described below:
V 1.2:
Speed 720kbps and it has backward compatibility with v1.1
V 2.0:
Speed 2.1 Mbps and it has backward compatibility with v1.2
V 2.1:
Speed 2 Mbit/s and it has backward compatibility with v1.2
V 3.0:
Speed 24Mbps and it has backward compatibility with v2.1
V 4.0:
Speed 24Mbps and it has backward compatibility with v3.0
V 4.1:
It is specially designed for LTE cellular technology.