The CONTOUR function displays a matrix of data as a contour plot. The most familiar use of contour plots is to show changes in terrain height on geological maps. But contour plots are not limited to showing heights. A contour plot may be used to show variations in resistance on a semi-conductor chip, heat distribution on the surface of an automobile, or ranges of amplitude (or power) in a sampling of speech data.
You can display a contour plot with labels as well as color shading in the background. See CONTOUR for more details.