key light

the main or primary light on a subject, often angled and off-center (or from above) that selectively illuminates various prominent features of the image to produce depth, shadows, etc.; high-key lighting (with everything evenly and brightly lit, with a minimum of shadows) is termed realistic (and often used in musicals and comedies), while low-key lighting (with less illumination, more shadows, and many grayish, dark areas) is termed expressionistic (and often used in film noir); three-point lighting uses: (1) a fill (or filler) light – an auxiliary light to soften shadows and areas not covered by the key light, (2) a back light behind to add depth to a subject, and (3) a bright key light