What type of wave is characterized by compressions and rarefactions?

A longitudinal wave is characterized by compressions and rarefactions because it propagates through the medium by means of particle displacement parallel to the direction of wave travel. In these waves, the areas where particles are close together represent compressions, while rarefactions are regions where particles are spread apart. This is typical of sound waves traveling through air or other mediums.

In contrast, transverse waves, such as those found in water or electromagnetic waves, involve particle motion that is perpendicular to the direction of wave travel, leading to crests and troughs rather than compressions and rarefactions. Surface waves, which occur at the interface between different media like air and water, exhibit characteristics of both transverse and longitudinal waves but do not specifically feature compressions and rarefactions in the same manner as longitudinal waves. Hence, the defining characteristic of compressions and rarefactions specifically aligns with longitudinal waves.