Chiaroscuro (Italian for light-dark) is a term in art for a contrast between light and dark. The term is usually applied to bold contrasts affecting a whole composition, but is also more technically used by artists and art historians for the use of effects representing contrasts of light, not necessarily strong, to achieve a sense of volume in modeling three-dimensional objects such as the human body.
The word Chiaroscuro itself is Italian, and roughly means, “light and dark.” It was first used to describe a type of drawing on medium-dark paper where the artist created both darker areas with ink and lighter areas with white paint.
Later on the term was used for woodcut prints which essentially did the same thing, using white and black together.
When it comes to painting, however, Chiaroscuro truly came to life in the paintings of Caravaggio during the late 16th century.
Caravaggio began to use deep, dark backgrounds for many of his paintings, and seemed to almost turn a spotlight on his figures. The high contrast in those paintings made for intensely powerful and dramatic works of art.
Because of Caravaggio, Chiaroscuro became very popular, and today the word is most often used to mean “high contrast” more than anything else.