Place a light behind your subject and point it toward the camera. The subject becomes a silhouette. That is a backlight, a light positioned behind the subject to create separation from the background or to outline the subject's shape. It is one of the fundamental tools of cinematography. Without it, a subject can blend into the background. With it, the subject pops off the screen.

Backlighting has many uses. It can create a rim of light along a character's hair and shoulders, separating them from a dark background. It can create a halo or angelic glow. It can create a mysterious silhouette, as in film noir. It can simulate sunlight flaring into the lens. It can hide a character's face in shadow while revealing their form. The effect depends on the intensity, color, and angle of the light.

Backlighting is not always flattering. A strong backlight can underexpose the subject's face. That is why cinematographers often pair a backlight with a fill light or a bounce to lift the shadows. The key light provides the main illumination, the fill light softens the shadows, and the backlight separates the subject from the background. That three-point setup is a standard starting point. The backlight is the least visible and often the most important.