Definition & Meaning of "key lighting"

What is "key lighting"?

Key lighting is the main light source used to highlight and define a subject in photography and film. It is positioned to create the primary illumination and set the overall mood and depth of the scene. The key light establishes the main exposure and shadows on the subject, shaping its features and creating contrast. By controlling the intensity, angle, and distance of the key light, photographers and filmmakers can achieve various effects, from dramatic and high-contrast looks to soft and even lighting.