The document discusses the functions and uses of color in visual communication. It outlines how colors can be used to attract attention through strength, create atmospheres, inform, structure, and teach. It also describes the natural color system which is based on how humans perceive color, using the color space, circle, and triangle to illustrate relationships between colors. Finally, it explains that color combinations from the same or adjoining quadrants in the color circle produce whispering or speaking colors, while combinations from opposite quadrants produce shouting colors.