What type of modulation is commonly used in most digital communication systems?

Phase Shift Keying (PSK) is a widely used modulation technique in digital communication systems primarily because it enables the transmission of digital data effectively by varying the phase of a carrier wave. In PSK, different phases represent different symbol values, allowing for efficient encoding of binary data. This method is particularly efficient in terms of bandwidth and is less susceptible to noise compared to other modulation techniques, such as Amplitude Modulation (AM) or Frequency Modulation (FM).

In digital communication, where the aim is often to transmit data securely and with minimal error, PSK provides a robust alternative due to its ability to distinguish multiple signal states while preserving the integrity of the signal over distance and through various mediums. Additionally, complex PSK variations, like Quadrature Phase Shift Keying (QPSK), allow the transmission of multiple bits per symbol, increasing data rates without requiring additional bandwidth.