A shadow is a dark area where light from a light source is blocked by an object. It occupies all of the three-dimensional volume behind an object with light in front of it. The cross section of a shadow is a two-dimensional silhouette, or a reverse projection of the object blocking the light.

Chhaya or Chaya is the Hindu personification and goddess of shadow, also called Sandhya and a consort of Surya, the Hindu sun god. She is the shadow-image or reflection of Saranyu (Sanjna), the first wife of Surya. Chhaya was born from the shadow of Sanjna and replaced Sanjna in her house, after the latter temporarily left her husband.