Shadow Play
Using cast shadows as the primary graphic element of a photograph.
In depth
Shadows require hard, directional light and a surface to fall on, so the technique belongs to low sun, single-source artificial lighting and strong architectural geometry. Because a shadow is a distorted projection, it can be far more graphically interesting than the object casting it, and photographing it alone often makes a stronger picture.
Examples in practice
Late sun through railings draws a striped pattern across a wall that becomes the subject rather than the railings.