In simple terms, the amplitude of a wave refers to the maximum displacement or height of the wave from its equilibrium or rest position. It measures the strength or intensity of the wave. For example, if you consider a water wave, the amplitude would be the maximum height of the wave crest above the undisturbed water level or the maximum depth of the wave trough below the undisturbed water level. In the case of a sound wave, the amplitude corresponds to the maximum displacement of air particles from their normal positions as the wave passes through. In general, the greater the amplitude, the more energy the wave carries.