A shadow is a dark area or shape that is created when an object blocks light from a source. Shadows are formed when light rays are blocked by an opaque object, such as a solid body or an opaque surface. The shape and size of a shadow depend on the angle and intensity of the light source, the distance between the object and the surface on which the shadow is cast, and the shape and size of the object itself. Shadows can be used to estimate the height, size, and shape of an object, as well as to create visual effects and artistic compositions. Shadows are also used in various scientific disciplines, such as astronomy, physics, and optics, to study the behavior of light and matter.