A stump is a cylindrical drawing tool, tapered at the ends and usually made of rolled paper, used by artists to smudge or blend marks made with charcoal, Conté crayon, pencil or other drawing media. By its use, gradations and half tones can be produced. Stumps are sold commercially in a range of sizes suitable for manipulations covering large areas, for operations on a miniature scale, and those in-between. Charcoal is the blackish residue consisting of impure carbon obtained by removing water and other volatile constituents from animal and vegetation substances. ... A Pencil. ...

While similar effects can be produced by smudging with one's fingers, this deposits oil from the skin onto the drawing surface, making the surface less receptive to the charcoal or other drawing medium.