Since light is a type of electromagnetic wave, it can be thought of as uniformly vibrating in all directions in a plane perpendicular to the direction of propagation. This type of light is called natural light (or natural polarized light). If the direction of vibration of natural light becomes polarized for some reason, that light is called polarized light. When natural light is reflected from the surface of glass or water, for example, the reflected light vibrates in one direction only and is completely polarized. Also, on a sunny day the light from the area of the sky at a 90º angle from the sun becomes polarized due to the effect of air molecules and particles in the atmosphere. The half-mirrors used in autofocus SLR cameras also cause light polarization.canonglossaryeu
Light waves that are restricted to vibrate in one plane and at right angles to their direction whereas non polarised light is random.