3 Point Lighting System

The key light, shines directly upon the subject and serves as its main light source. The Sun often serves as a key light.

The fill light also shines on the subject, but from a side angle relative to the key and is often placed at a lower position than the key (about at the level of the subject's face).
It is usually softer and less bright than the key light.

The back light shines on the subject from behind, often to one side or the other. It gives the subject a rim of light, serving to separate the subject from the background and highlighting contours.