Polarization

A wave is polarized if it can only oscillate in one direction or plane. A wave can be polarized by the use of a polarizing filter. The polarization of a transverse wave describes the direction of oscillation in the plane perpendicular to the direction of travel.
Longitudinal waves such as sound waves do not exhibit polarization. For these waves the direction of oscillation is along the direction of travel.

Examples of waves include:
• Ocean surface waves, which are perturbations that propagate through water
• Radio waves, microwaves, infrared rays, visible light, ultraviolet rays, x-rays, and gamma rays, which make up electromagnetic radiation; can be propagated without a medium, through vacuum; and travel at 299,792,458 m/s in a vacuum
• Sound — a mechanical wave that propagates through gases, liquids, solids and plasmas
• Waves of traffic, that is, propagation of different densities of motor vehicles, and so forth, which can be modeled as kinematic waves, as first presented by Sir M. J. Lighthill earthquakes, of which there are three types, called S, P, and L
• Gravitational waves, which are nonlinear fluctuations in the curvature of spacetime predicted by General Relativity, but which have yet to be observed empirically
• Inertial waves, which occur in rotating fluids and are restored by the Coriolis effect