"If it can be written, or thought, it can be filmed..." STANLEY KUBRIC
From Encyclopedia PRO
The background lighting is a lighting technique that is used to illuminate the background area of a set. Sometimes the impact of the picture is not in the subject but in the foreground or background. Background lighting allows the viewers to take into account the background actions which are linked to the character's actions.
In the standard 4-point lighting setup, the background light is placed last and is usually placed directly behind the subject and pointed at the background.