Three Point LightingThe most basic lighting technique used in cinema is the three-point lighting system. It was developed during the Hollywood big studio era and is still widely practiced throughout the world. Three point lighting creates a very natural, realistic look to the scene. The primary light source, or key light, illuminates the dominant subject in the shot. This draws the viewers’ eye directly to that point because it is the highest point of contrast, usually of light and shadow. A cinematographer sets the key light up to direct attention towards the shot’s focal point of action, either psychological or physical. It is the brightest light, usually positioned to illuminate the side of the person's face that isn't directly facing the camera.
Fill lights, which are approximately half as bright as the key lights, soften the harshness of the key light. This soft, diffused light, is often bounced off a reflective umbrella, or shined through a sheet of diffusion or softbox. This light is gentler on the subject than the key light, and it fills in the shadows of the key light. It's used to illuminate the side of the face opposite the key light, and reveals subsidiary details that would otherwise be hidden in shadow.
The third point of the three point lighting system is the backlight. Backlights work to separate the foreground from the background, creating a great depth of field. Without a backlight the image would appear very flat and two-dimensional. These three lights are used together to create the most realistic shot possible, and although seen as one of the most basic lighting techniques, is still used in many major films today.