The Three Point Lighting Technique is a standard method used in visual media such as video, film and still photography. It is simple but versatile which forms the basis of most lighting. The technique uses three lights called the key light, fill light and back light.
Back Light - The back light provides separation from the subject and the background. It can be used to create an outer glow or a silhouette.
Key Light - The key light is the primary light source of the subject and provides the base light.
Fill Light - The fill light provides some fill to the shadow are of the subject to balance out the contrasts created by the key light. This technique is often used in order to light a scene where the characters are indoors at night. It is a way to create tension or suspense, particularly causing narrative enigma in the thriller genre.