Phase Modulation is a technique used in communication systems to encode information by varying the phase of a carrier wave. Instead of changing the amplitude or frequency, the phase of the wave is shifted to represent different data values. This allows for efficient transmission of information over various media, such as radio waves. In digital communication, phase modulation can be particularly effective because it is less susceptible to noise compared to other modulation methods. By using discrete phase shifts, it can convey multiple bits of information per symbol, making it a popular choice in technologies like Wi-Fi and cellular networks.