Light is the interaction of electric and magnetic fields traveling through space. The electric and magnetic vibrations of a light wave occur perpendicularly to each other. The electric field moves in one direction and magnetic field in another though always perpendicularly. So, we have one plane occupied by an electric field, and another plane perpendicular to it by a magnetic field, and the direction of travel which is perpendicular to both.

A light wave that is vibrating in more than one plane is known as unpolarized light. Many common light sources such as sunlight, Light Emitting Diode (LED) spotlights, and incandescent bulbs produce unpolarized light.

Because light is a transversal wave it can be polarized. The process of transforming unpolarized light into the polarized light is known as polarization. When the electric field vectors are restricted to a single plane by filtration, then the light is said to be polarized with respect to the direction of propagation and all waves vibrate in the same plane. The most common source of polarized light is a laser. In a transverse wave, the direction of the oscillation is perpendicular to the direction of motion of the wave. Hence, polarization is a property applying to transverse waves.