A smooth blending of shades from light to dark or from color to color. Also called a "fountain fill," in 2D drawing programs and paint programs, gradients are used to create colorful backgrounds and special effects as well as to simulate light and shadows. In 3D graphics programs, lighting can be rendered automatically by the software. See
3D graphics.
A Gradient
The software generates the gradient automatically as in this example created in Photoshop.