A sketch is a rapidly executed free hand drawing that is not usually intended as finished work A sketch may serve as a number of purposes It might record something that the artist sees it might record or develop an idea for later use or it might be used as a quick way of graphically demonstrating an image idea or principle Sketches can be made in any drawing medium The term is most often applied to graphic work such as Silverpoint Graphite pencil charcoal or pastel It may also apply to drawings executed in pen amp ink digital input such as a digital pen ballpoint pen marker pen water colour and oil paint The latter two are generally referred to as water colour sketches and oil sketches A sculptor might model three dimensional sketches in clay plasticine or wax