Phase Modulation (PM) is a technique used in communication systems to encode information by varying the phase of a carrier wave. In PM, the phase of the signal changes in response to the amplitude of the input signal, allowing for the transmission of data over radio waves or other mediums. This method is commonly used in digital communication systems, such as television broadcasting and satellite communications. One of the key advantages of PM is its resistance to noise, making it suitable for long-distance transmission. By altering the phase rather than the amplitude, PM can maintain signal integrity even in challenging conditions. This technique is closely related to Frequency Modulation (FM), where the frequency of the carrier wave is varied instead of the phase.