Chiaroscuro — from the Italian 'chiaro' (light) and 'scuro' (dark) — is the technique of using strong contrasts between light and shadow to model three-dimensional form on a flat surface. The practice existed in antiquity, but it was Leonardo da Vinci who first theorised it systematically, calling it 'sfumato' in its softest form. Caravaggio took it to its dramatic extreme in the 1590s: his figures emerge from absolute blackness, lit as if by a single candle, creating an almost cinematic tension unknown before him. Rembrandt brought it north, softening the drama into warmth. In cinema, film noir — with its raking shadows and high contrast — is chiaroscuro translated into light and celluloid. To understand chiaroscuro is to understand how artists learned to make a flat surface feel inhabited.