Planetshine is the dim illumination, by sunlight reflected from a planet, of all or part of the otherwise dark side of any moon orbiting the body. Planetlight is the diffuse reflection of sunlight from a planet, whose albedo can be measured.
The most observed and familiar example of planetshine is earthshine on the Moon, which is most visible from the night side of Earth when the lunar phase is crescent or nearly new, without the atmospheric brightness of the daytime sky. Typically, this results in the dark side of the Moon being bathed in a faint light.