Soft light is a quality of illumination characterized by gradual, gentle transitions between lit and shadowed areas, with no hard edges to shadows and a wrapping, diffused quality that reduces contrast and smooths surface texture. It is produced when light comes from a large source relative to the subject, or when direct light is scattered and spread by a diffusing material before reaching the subject.

The size of a light source relative to the subject determines its softness: a large source close to the subject produces very soft light, while a small source far away produces hard light with sharp shadow edges. In practice, soft light is created using large softboxes, diffusion panels placed over lights, reflectors that bounce and scatter light, overcast sky conditions that turn the entire sky into a vast diffuse source, or by placing subjects near large windows with indirect daylight. Soft light is frequently associated with flattering portraiture, romantic and tender emotional tones, and clean commercial photography because of how it smooths skin texture and creates gentle, appealing dimensional modeling without harsh shadows. It is distinct from high key lighting, which refers to the overall brightness level of a scene, though soft light is often used in high key setups.

In AI generation prompts, soft lighting descriptions reliably shape the visual quality of outputs. Terms like "soft diffused light," "overcast lighting," "large softbox illumination," "window light," or "gentle wraparound lighting" communicate this quality clearly and help produce imagery with the characteristic smooth transitions and reduced contrast of well-executed soft light setups.