This is an Italian term which literally means ‘light-dark’. In paintings the description refers to clear tonal contrasts which are often used to suggest the volume and modelling of the subjects depicted.
(definition from ) https://www.nationalgallery.org.uk/paintings/glossary/chiaroscuro
Tintoretto ( 1518 – 1594).
The light in this painting serves to draw our attention on the figures the artist wishes us to focus on. Light picking out edges of objects in the background only, giving the effect of depth.
In this example of a self portrait the background is completely solid the light serving to illuminate the face pushing it forward toward us.
Peter Paul Rubens [Public domain], via Wikimedia Commons
There is a little detail in the background in the Night Scene, more of a feel that the characters are in a room. The light coming from the candle showing us the faces and the clothes. This feels more intimate than the grander pictures as if we are sharing the moment.
Joseph Wright of Derby 1734-1797
English Portrait and Landscape painter. Acclaimed as the first painter to encompass the spirit of the industrial revolution.
Fabulous depth, the light picks up limbs and clothing at different distances from the eye. Muted colours, almost sepia. The black in the top left corner darkest with the arch behind and its darkness soft.