What does the term 'key light' signify in stage lighting?

The term 'key light' signifies the primary and most important light source used in stage lighting. It is responsible for highlighting the features of the subject on stage, creating depth and dimension, and establishing the overall mood of the scene. The key light is typically the brightest light and is positioned to illuminate the subject in a way that enhances visual clarity and artistic expression.

In contrast, lighting used for effects focuses on creating specific visual moments and enhancing particular elements, while a secondary source of lighting, often referred to as fill light, is designed to soften shadows created by the key light. Backlighting serves a different purpose by illuminating the subject from behind, often to create a silhouette effect, which contrasts with the role of the key light in defining the subject's appearance. Thus, the key light's dominance in stage lighting plays a crucial role in the effective portrayal of characters and scenes in a production.