A pencil is a writing or drawing instrument consisting of a thin stick of graphite and clay, usually encased in a thin wood cylinder. Pencils are distinct from pens, which use a liquid marking material. The archetypal pencil may have been the ancient Roman stylus, which was a thin metal stick, often made of lead and used for scratching on papyrus. The word pencil comes from the Latin word pencillus which means "little tail."