Lighting is an essential part of filmmaking that influences the audience's emotional reaction. The angle and quality of light provides clues about the scene's time and location. Lighting also impacts the audience's perception of the film's production value. A scene can be lit by available natural light or artificial lights. Hard lights from small sources like spotlights create harsh shadows while soft lights from large sources create a gentle look. Effective lighting in films typically uses a minimum of four light sources, including a key light that provides the main brightness, a fill light to reduce shadows, and a back light to outline the subject.