Hard shadow cast by an object or actor onto a surface — floor, wall, background. Defines light direction and adds depth; separate from object's own shade.
The hard shadow that an object or person casts onto a surface—this is the tool with which you make light direction legible. Not to be confused with the object's own shadow (the dark side of the object itself), but rather the sharp or diffuse projection behind it. On set, the quality and placement of this cast shadow determine the entire spatial logic of a scene.
In practice: You position your key light, and the cast shadow immediately shows where the light is coming from. If it's sharp and dark, you have hard, direct light—spotlights, sun without diffusion. If it's soft, gradual gray, a large surface or a cloudy sky is working for you. That's why we constantly observe cast shadows: they are the most honest statement about your lighting situation. A shadow falling to the right tells the viewer in milliseconds that the light source is positioned top-left—without you having to explain it.
For depth of field, the cast shadow is invaluable. An actor whose shadow clearly falls on the floor is spatially in the set, not in front of a green screen. That's why we often shoot in studios with elevated overhead lighting—not just for illuminating the face, but because we need the foot shadow. With extreme backlighting, dramatic long cast shadows are created that build tension (see also: Silhouette, Backlight Motivation).
Caution in practice: Multiple light sources create multiple cast shadows—this can appear chaotic or, if used deliberately, work atmospherically (Bartczak Effect for the neon look). When shooting with a green screen, you must add artificial cast shadows, otherwise the composition will later appear floating and unanchored. In digital editing, you can also enhance or weaken cast shadows through color correction—but the shape and direction should already be correct during the shoot.