Lighting is an important signifier as it conveys the mood or atmosphere of the scene which we are observing. In a studio, the lighting is usually from three sources and is set up as follows:

a) The key light , as the name suggests, is usually the brightest and most influential.
b) The back light helps counteract the effect of the key light, thus making the figure look more 'rounded'.
c) The filler light helps to soften the harsh shadows created by the use of the back and key lights. There may be more than one of these.

The director manipulates this basic format to attain the atmosphere he wishes to signify. For instance, if he uses only the key and back lights, he will produce a sharp contrast of dark and light areas on the screen as shadows are formed. This is known as low-key lighting. Exaggerated use of low-key lighting can be found in horror films, where underlighting (placing a light under a face or an object) gives a dramatic effect. Low-key lighting is often seen as expressive. High-key lighting means that filler lights are used. This will appear much more normal to our eyes but can also be manipulated to give a more glamorous look to a star's face, or add a 'twinkle' to their eyes. It is much 'softer' than low-key lighting.