chapter  11
WithAjawad I. Haija, M. Z. Numan, W. Larry Freeman
Pages 27

Ordinary light is emitted by atoms that radiate when they experience a change in their energy state. Thus, the electric field vectors in these waves have all directions. This is the characterization of an unpolarized light, also called ordinary or natural light. Polarization, in contrast, means selective directions of oscillation of the electric field in the EM waves.