please xplain polarization of light . i am unable to understand it .

It is well known from Electromagnetic theory that light is an electromagnetic wave, with the electric and magnetic fields vibrating in a plane perpendicular to direction of propagation of the wave, and also perpendicular to each other. Conventionally, the direction of the electric field vector  (in the plane perpendicular to direction of propagation) is called the direction of Polarization of light. Ordinary light is unpolarized, which actually means that the electric field does not oscillate along a particular direction, but randomly keeps changing direction. However, if this vector lies along a fixed direction, light is called linearly polarized or plane polarized.