Open Shade
An area shielded from direct sun but open to a large expanse of sky, giving soft, even illumination.
In depth
Open shade is the simplest good light available outdoors: the effective source is the entire visible sky, which is enormous and therefore very soft. Two cautions apply — the light is strongly blue and needs white balance correction, and standing under a tree rather than beside a building adds green casts and dappled highlights.
Examples in practice
Moving a portrait subject from harsh sun into the shadow of a north-facing wall replaces squinting and hard shadows with even light.