The system of chiaroscuro is a tool to help the artist better render the illusion of a three-dimensional form on a two-dimensional service. The use of this system goes back to Renaissance Italy, if not earlier.
The term chiaroscuro comes from Italian. The first part of the word, chiaro, means light and the second part of the word, scuro, means dark. The term refers to the careful use of light and dark to create the illusion of form.
The system requires that the artist represent the following six parts to create the illusion of three-dimensionality.
The following labelled examples show the system of chiaroscuro to render basic three-dimensional forms. After mastering the basic shapes, the system can be applied to more complex forms. Chiaroscuro forms the basis for creating the illusion of three-dimensionality throughout much of painting and drawing in the Western world.

It is often easiest to build up the values slowly, as in the following example.


More complex form created using chiaroscuro
More complex form created using chiaroscuro
More complex form created using chiaroscuro
One problem artists run into is getting contrast right. Often students struggle with including enough darks. Sometimes it is necessary to push the darks, or make them darker than you think you need at first look. Here is a cheesy video clip from the 1980s movie Legend to help you remember, Light and Dark. And yes, that is Tom Cruise and Tim Curry. In order to have the illusion of light, one must have dark. As Tim Curry states, they are eternally connected.