The HC-06 is used to add Bluetooth functionality to your devices & to replace serial port communication.

Features:

Operating voltage: 3.6 to 6Vdc.
Operating current: 30mA.
Communication distance: 10 meters.
Working mode: slave.
Passcode: 1234.
Full-duplex serial interface.
Communication format:  Only supports 8 data bits, 1 stop bit, no parity.
Default baud rate: 9600 bps.
Dimension: 16 x 38 mm.
Weight: 5g.

Status LED indicator:
 1) LED flashes = Bluetooth is not connected.
 2) LED on = Bluetooth is connected.

Pinout:
 1) RXD = Receive data (In) - Connect this pin to Arduino board's TXD pin.
 2) TXD = Transmit data (Out) - Connect this pin to Arduino board's RXD pin.   
 3) GND = Ground
 4) VCC = 3.6 to 6V