Light flowing into the eyes is perceived by the mind as an interplay of shapes with color, size, dimension, perspective, and meaning.
Color is integral to human perception.
Without color, shapes lose clarity and meaning because the mind perceives shape by noticing subtle changes in color. One reason the paintings of Vincent van Gogh are so popular is that he makes magical use of color to form shapes and images that swirl and blend and come alive on the canvas. Color is an important communication tool when used carefully on web pages and in programs. Most work with color is device-dependent meaning that colors created on one hardware platform do not look the same when shown on another hardware platform. Even a good reproduction of van Gogh's The Starry Night does not really capture the color, texture, and magic of the original.