Phase shift keying is the modulation scheme that will change the phase over the carrier signal being sent and received. The signal is converted into the magnetic field by varying its sine cosine inputs at a time.

It is being used for RFID,Bluetooth,LAN communication.

Digital modulation always wants finite set of the data to process. So finite number of phases are being considered, and all these patterns are assigned by the binary digits. The encoding is the same for each number of bits.

Each pattern of bits forms the symbol that is represented by the particular phase.

The demodulator determine the right phase of the signal received ,and provides mapping for the symbol it represents for recovering it.