Lighting research

The Three Point Lighting Technique is a standard method used in film, still photography and computer-generated imagery. Lighting is a very important aspect  in film making and can be used to create an atmosphere without much effort.

Three types of lighting in film making
Key Light - This is the main light. It is usually the strongest and casts the most light on the scene. It is placed to one side of the camera/subject so that this side is well lit and the other side has some shadow.
Fill Light - This is the secondary light and is placed on the opposite side of the key light. It is used to fill the shadows created by the key. The fill will usually be softer and less bright than the key. 
Back Light - The backlight is placed behind the subject and lights it from the rear. Rather than providing direct lighting (like the key and fill), its purpose is to provide definition and subtle highlights around the subject.