Eight Phase Shift Keying (8PSK) is a modulation technique employed for transmitting digital data over a carrier signal by altering the phase of the carrier. In 8PSK, a set of eight distinct phase changes is defined, and each of these phase changes corresponds to the transmission of 3 bits of information. 8PSK is utilized in various applications, including EDGE (Enhanced Data rates for GSM Evolution).

The defined phase changes in 8PSK are as follows, measured in degrees: 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°.