What defines the crest of a wave?

The crest of a wave is defined as the highest point of the wave. In wave terminology, the crest is the peak where the displacement of the medium is at its maximum in the positive direction. This is in contrast to the trough, which represents the lowest point or the maximum negative displacement. Understanding the concept of a wave involves recognizing that waves oscillate between these extreme points: the crest and the trough. The distance between two troughs pertains to the wavelength but does not relate to the definition of the crest itself. Similarly, the midpoint of the wave refers to the equilibrium or resting position of the medium, which is not indicative of the peak amplitude that the crest represents. Thus, the identification of the crest as the highest point clarifies its role in the overall structure and behavior of waves.