A sundial is a device used to tell time by the position of the sun’s shadow. It works by casting a shadow on a flat surface with a stick or pointer, called the “gnomon,” which is positioned at an angle relative to the Earth’s axis. As the sun moves across the sky, the shadow of the gnomon shifts, and the position of the shadow on the sundial’s face indicates the time of day.
Sundials were one of the earliest methods of timekeeping and were widely used before mechanical clocks were invented. They work best when placed in a location that receives consistent sunlight, and their accuracy can be affected by the season, geographical location, and the tilt of the sundial.