^Ordinary or unpolarized light
Light is made up of the superposition of a huge number of light waves emitted by individual atoms whose electric fields are in random directions. As a result the direction of vibration (DOV) of electric field vector at any given point of space keeps on changing very rapidly & randomly but always remain perpendicular to the direction of propagation (DOP). Such a light is called randomly polarized or simply unpolarized light. If a light wave propagates along x axis then tip of the electric field vector traces an irregular planar curve & there can be infinite directions of vibrations of electric field vector in the yz plane as shown in the diagram.
Light from a light bulb, candle, Sun is unpolarized. Usually we represent electric field vibrations in a ordinary light by dots & double arrows. Here double arrows represent the vibrations in the plane of paper (let xy plane) i.e. along ± y – axis and small dots represent vibrations perpendicular to the plane of paper along i.e. ± z – axis.