Shape builds on line and color, as it has to be made of one or both of these. Shape is the property of a two-dimensional form, usually defined by a line around it or by a change in color.
There are two main types of shapes, geometric and organic. While most works of art contain both geometric and organic shapes, looking at those that are more completely divided can serve to clarify these qualities.
Piet Mondrian is an excellent example of an artist who used geometric shapes almost exclusively. In his Composition with Yellow, Blue and Red (1937-42), Mondrian, uses straight vertical and horizontal black lines to divide his canvas into rectangles of primary colors.
Nothing here gives the impression of the natural world. On the other hand, Maori facial tattooing, known as moko, uses primarily organic shapes. They are still, like Mondrian’s shapes, generally abstract — they do not depict any clear images — but the shapes are like those found in nature, curving, twisting, and spiraling across their wearers’ faces. The edges of the lines and shapes are crisp, but the forms are curving and sensuous.
Form is actual, three-dimensional shape, though it is often used to describe the illusion of three-dimensionality, as well. Like shape, form can be geometric or organic.
A small korwar — a representation of an ancestor — from Irian Jaya, New Guinea, mixes these form types well. While the figure is predominantly geometric, with the head shaped like a cube and the nose an arrow pointing downward, the curving organic lines around the eyes soften this effect a bit.