What is the role of the 'key light' in a three-point lighting setup?

The key light is indeed the main and brightest light source in a three-point lighting setup. Its primary function is to illuminate the subject and establish the overall mood and visibility. By providing a strong, focused beam of light, the key light shapes how the audience perceives the subject. It highlights the subject's features and can create a sense of drama through shadows and highlights, which are crucial for effective storytelling in visual media.

This setup typically includes other lights, such as the fill light, which softens shadows created by the key light, and the backlight, which adds depth and separates the subject from the background. However, it is the key light that serves as the foundation for the entire lighting arrangement, effectively setting the scene's tone and focus.