A pencil is an instrument used for writing, drawing, marking, or coloring which employs a dry medium in contrast to a pen (ink pen or ball point pen) which uses a liquid or wet medium. The actual writing medium used in the modern pencil consists of a graphite and clay mixture which is fused into rods of various grades of hardness or softness. The modern process of production owes its origins to a process (the Conte process) which was first discovered in the late 18th century.
Colored pencils are primarily for art, and do not use graphite, but various wax or water-soluble bindings for colored pigments.
In spite of predictions of its imminent demise due to the increased usage of the Internet for communication, world-wide pencil production remains strong at some 14 billion pieces per year.
Pencil "leads", as they have come to be called for historical reasons, are manufactured in a wide variety of grades, quality, and price, but the pencil itself has come to take one of two basic forms, namely, the wood-cased pencil and the mechanical pencil.
In the first-mentioned instance, a long thin rod of graphite (cum binder) is surrounded by an enclosure of wood which is most often finished with coatings of varnish or laquer. As the pencil is used, the graphite writing medium is further exposed by shaving off the wood enclosure. With a mechanical pencil, a thin rod of graphite is inserted into a specially designed metal holder. As the writing substance of the pencil is used, further lengths are exposed either by pushing the rod of graphite further out or by releasing a claw-like gripper and allowing it to slide freely out until the gripper is re-engaged. The exact process by which this is accomplished in either case depends on the design of the mechanism.
There are several different and common usages of the pencil in modern times. First, it can be used in ordinary writing, much like a ball point or ink pen with this difference: the pencil markings are erasable which is not usually the case with the pen. The erasability feature makes the pencil an ideal choice for making rough drafts, sketches, or notes, sometimes as a preliminary towards more permanent fixation in ink.
For art and technical work, pencil graphite is commonly rated from the softest (9B) to hardest (9H). In general use, pencils are also given numbers; a #2 is the same as the technical HB designation.
Engineers employ pencils of harder grades (and thus a finer point) in the making or labelling of technical drawings. Artists will use a much wider range of grades of pencils in artwork, either as preliminary sketches before being filled in with ink or as finished products in their own right (pencil drawings).
Finally, craftsmen and carpenters make use of the pencil in marking or otherwise laying out their work. Carpenter pencils often have a flat wooden case and an elliptical graphite core, so broad lines can be drawn.