Shape is defined as a two-dimensional area or mass delimited by contour lines. There are two main types of shapes: geometric shapes which follow mathematical patterns and transmit order, and organic shapes which have irregular profiles and convey more dynamism. Shapes can also be open or closed, and positive or negative. The key parts of a shape include the outline/contour, silhouette, and infill. Shapes are used to create the illusion of three-dimensional space by suggesting visual cues of distance and depth.