Complicated objects can usually be imagined as the combination of a few simple shapes. Similarly, it is often helpful to reduce complex relationships of forms within an image to a few clear contours. Artists use these simpler outlines to provide an overall structure. It's like building scaffolding on which to "hang" all of the various parts of an image. Organizing the main elements in this way can allow the artist to control the balance, rhythm and focus. It establishes a sense of harmony and unity by structuring the placement of forms in a composition.
