Transverse and longitudinal waves are two major forms of waves. A transverse wave can be created by shaking a string or rope up and down. Although the string moves up and down, the wave itself and its energy moves away from the source, perpendicular to the direction of the oscillations.

The oscillations in longitudinal waves move in the same direction that the wave is moving. The medium in longitudinal waves alternately pushes close together (compression) and separates from each other (rarefaction). The best example of longitudinal waves are sound waves, which are a series of back and forth longitudinal oscillations of atoms or molecules that form alternate regions of high and low pressure in a medium such as air.

Water waves are a combination of transverse and longitudinal waves that move in circles. Just as in the case of transverse and longitudinal waves, energy is transferred but matter is not moved.