Polarization is a property that is inherent to all vector waves. Light, as a transverse electromagnetic wave, has an electric field that oscillates perpendicular to the direction of propagation. Light is considered unpolarized when the direction of electric field fluctuates randomly over time. Common sources of unpolarized light include sunlight, halogen lamps, LED spotlights, and incandescent bulbs. In contrast, when the electric field fluctuation is well-defined, light is referred to as polarized light. The most common source of polarized light is a laser beam.