What is the technique that utilizes key, fill, and hairline lights to illuminate a subject?

The technique that employs key, fill, and hairline lights to effectively illuminate a subject is known as Three Point Lighting. This method is widely used in photography, film, and television production because it provides a balanced and dimensional lighting setup that enhances the appearance of the subject.

The key light is the primary source of illumination, creating the main highlights and shadows on the subject. The fill light then softens these shadows, ensuring that details are visible without overpowering the overall brightness. Lastly, the hairline light, or backlight, adds separation between the subject and the background, outlining the subject's features and creating depth. This combination results in a well-lit subject with a visually appealing three-dimensional look.

Other lighting techniques, such as flat lighting or side lighting, may serve specific purposes but do not offer the comprehensive versatility and balanced look that Three Point Lighting achieves through the distinct roles of each light source.