Showing change from light to dark or dark to light in a picture by darkening areas that would be shadowed and leaving other areas light. Blending of one value into another is sometimes called feathering. Shading is often used to produce illusions of dimension and depth.About shading: "By adding darkness to the edge of an object on the side that faces away from your light source, you will push that edge away from your eye. If I had to choose one of these twelve words that I thought was the most important, I would choose shading. Shading is a power word for Ninja Power Artists. With shading, you can make any drawing, even a flat 2-D picture, look super-three-dimensional! " Mark Kistler, American TV artist / instructor."The Twelve Renaissance Words of Drawing in 3-D," 1997.Also see chiaroscuro, gradation, modeling, penumbra, perspective, shade, and three-dimensional.