Sundials consist of two parts, a face containing the hours of the day, plus a wide range of decorative motifs, and a gnomon, or shadow arm. Usually mounted on a stand, a sundial may also be set on a wall or on the ground. The face should be horizontal to the earth with the gnomon and the 12:00 position on the dial pointed north. To "set" the sundial, turn it until the shadow falls on the current standard time.