What type of wave has its wave form moving in one direction along the surface of a transmission medium?

A progressive wave is characterized by the movement of its wave form through a medium in a specific direction. In the context of wave motion, this means that energy is transferred from one location to another as the wave propagates through the medium. For example, when you throw a stone into a calm body of water, the ripples that move outward from the point of impact illustrate the behavior of a progressive wave.

Unlike standing waves, which are formed by the interference of two waves traveling in opposite directions and result in fixed points of no movement (nodes), progressive waves continuously transmit energy and do not exhibit these stationary characteristics. Both transverse waves, which move perpendicular to the direction of energy transfer, and longitudinal waves, which move parallel to the energy transfer, can be progressive in nature; however, the defining feature of a progressive wave is the unidirectional movement of the wave form through a medium. This distinguishes it from the other categories of waves that do not share this specific trait of propagation.