In general, sundials indicate the time by casting a shadow or throwing light onto a surface known as a dial face or dial plate.  Although usually a flat plane, the dial face may also be the inner or outer surface of a sphere, cylinder, cone and various other shapes.

The time is indicated where the shadow or light falls on the dial face, which is usually inscribed with hour lines.  Although usually straight, these hour lines may also be curved, depending on the design of the sundial. 

By tradition, many sundials have a Motto.  The motto is usually in the form of an epigram: sometimes sombre reflections on the passing of time and the brevity of life, but equally often humorous witticisms of the dial maker.  Many contain the image of the sun, father time, or Roman Numerals.

Sundials are very often ornamental objects in a flower garden.  They can be a great conversational piece; very few people will rely on them for telling time.