Backlight

Light from behind the subject, rimming the edges with brightness. Separation from the background, and the halo of every remembered face.

Backlight solves the flat image's core problem: subject and background merging into one plane. A source behind the figure draws a bright seam along hair and shoulders, and the form lifts off the world behind it. Depth, in a medium that has none, is largely this seam.

It is also cinema's oldest tenderness: the rim of light around a face is how films say this one matters. Dust and atmosphere ignite in backlight, which is why our mağara and projection imagery leans on it. The craft is motivation and restraint, a rim with no source reads as heaven's gaffer, welcome in myth, suspect in realism.