Sometimes an etching - another 2-dimensional art form - is done by scratching through a "ground" that has been placed on a rectangular metal plate. This again will show up in two colors, when printed, like black and white, and thus is sometimes called a graphic art.
Even today one will see an etching that has been rendered in "crosshatch", and thus an artist can apply tons of shading, and to many and various degrees, unlike the woodcut.
Historically speaking many etchings were done, even for rough sketches, by some of the finest and most famous artists, say back in the Middle Ages; send me a comment and let me know if you have some of those famous names!
Sometimes the "ground" can be a SOFT ground, which means a person can "draw" through it with say, a match, from a book of matches - as I have done - instead of scratching through a hard ground on the plate. This can represent a much more casual or "free" mode of drawing.