Adaptive Differential Pulse Code Modulation (ADPCM) is a signal compression technique used primarily in audio and video data. It works by encoding the difference between successive samples rather than the samples themselves, which reduces the amount of data needed for transmission or storage. This method allows for efficient use of bandwidth while maintaining sound quality. ADPCM adapts to changes in the signal by adjusting the quantization levels based on the characteristics of the input. This adaptability helps to optimize the encoding process, making it suitable for various applications, including telecommunications and audio streaming.