A pencil is a writing or drawing instrument consisting of a thin stick of pigment (usually graphite, but can also be coloured pigment or charcoal) and clay, usually encased in a thin wood cylinder, though paper and plastic sheaths are also used. The word pencil comes from the Latin word pencillus which means "little tail". Modern pencils are made industrially by mixing finely ground graphite and clay powders, adding water, forming long spaghetti-like strings, and firing them in a kiln (thermally insulated chambers). Many pencils across the world and almost all in Europe are graded on the European system using a continuüm from "H" (for hardness) to "B" (for blackness), as well as "F" (for fine point). The standard writing pencil is graded HB.