Quadrature Phase Shift Keying (QPSK) is a digital modulation technique used in communication systems to transmit data efficiently. It encodes information by varying the phase of a carrier wave, allowing four distinct phase shifts, each representing two bits of data. This enables higher data rates compared to simpler modulation schemes like Binary Phase Shift Keying (BPSK). QPSK is widely used in various applications, including satellite communications and wireless networks. Its ability to transmit more data in the same bandwidth makes it an attractive choice for modern communication systems, balancing performance and complexity effectively.