Tone refers to the range of shades from light to dark used in a black and white photograph. Using dark and light areas creates a sense of depth. Lines imply motion and direction, and converging lines make a two-dimensional image appear three-dimensional. Shapes are defined by closed lines or color areas. Form and volume refer to how a three-dimensional object appears in a two-dimensional photograph, either as occupied or unoccupied space. Patterns create unity and structure by repeating elements such as lines, shapes, and colors. Texture describes the surface quality of an object, either actual or implied.