PAM4, or Pulse Amplitude Modulation with 4 levels, is a digital signaling technique used to transmit data. It encodes information by varying the amplitude of the signal in four distinct levels, allowing it to represent two bits of data per symbol. This method increases the amount of data transmitted over a given bandwidth compared to traditional binary signaling. PAM4 is particularly useful in high-speed communication systems, such as data centers and fiber optic networks. By enabling higher data rates without requiring additional bandwidth, PAM4 helps meet the growing demand for faster and more efficient data transmission in modern technology.