Polarization (also polarisation) is a property of transverse waves. Some waves have motion in another direction as well as the direction of the wave. In water, for instance, the wave will move across the water, but the wave will also move water up and down on the surface. Light waves are similarly transverse waves though they are also particles. Sound waves do not have polarization, since they are longitudinal waves. Polarized sunglasses take advantage of these oscillations.