A contour line in a piece of artwork is an individual line that delineates the edge or outline of one of the main shapes or forms in the image. A contour line is usually drawn with a pencil or pen rather than a brush.
A contour line is typically narrow and continuous, and it may vary in width to create the illusion of some parts being closer to the viewer. It marks the edge of an object or shows the border between objects in an image. Contour lines may also be used to show smaller shapes within larger ones. For example, individual facial features may be drawn in contour within a larger contour drawing of a person's head or figure.