Negative space is most commonly used in artistic circles. It is the empty, or passive, areas of a picture that remain after the positive image has been drawn. The words “empty” and “passive” may lead one to believe that negative space is somehow “second-class” and does not need attention, but this is not so. The negative space of a piece can make or break that work of art. If the negative space is left as it is, the piece may appear bland or flat. By paying careful attention to negative space, an artist is able to transform their picture into something extraordinary.
Negative space is not a backdrop for the positive space of a picture. Material conditioning of our culture has taught us to see anything not prominent as being subsidiary. This is most often seen in untrained artists' works. Instead of seeing negative space as an integral part of an art work, they see it as only a backdrop and so the negative space gets little attention.
Whenever a positive shape is being drawn on a sheet of paper, the negative shape is also being formed. This should be considered when an artist begins to work. It will determine the format of the piece, its scale, and positioning. By understanding the concept that positive and negative space affect each other directly, the visual potential of a piece of art is realized by the artist, resulting in a better piece of art. The decisions about how best to break up the surface of a picture plane into positive and negative shapes are among the most creative of the drawing process.
* source: Drawing Space, Form, and Expression- Wayne Enstice and Melody Peters
**an example of negative space was provided by SharQ (thank you SharQ!): http://www.kamps.org/hidden/e2/negspa.jpg