Fireman's Hat Tree
A shape is a closed line forming geometric or free-form/natural areas in space. Shapes may be two- or three-dimensional.
Shapes have length and width and may show perspective. Shape as a closed line may also perform some of the duties of lines,
giving direction and leading the observer visually. Circles and rectangles are examples of shapes.

Seven Elements of Design | eHow http://www.ehow.com/list_7676900_seven-elements-design.html#ixzz2TVLgQPhV