A sketch is a rough draft of an entire piece of art work or of part of a work. Sketching not only allows the artist to see the idea prior to commencing the final piece, but also to work out details such as perspective, scale, composition, lighting and so forth. Landscape artists frequently use sketching to determine the lighting of a particular scene. The sketches of some artists such as Rubens and Constable are nearly as valuable as their finished works.
A sketch-book is comprised of anywhere from twenty to fifty pieces of paper that have been bound together and are usually no larger than l0" by 15". The small size of sketch-books makes them easily carried by an artist so that any ideas or scenes that they may have or see can be quickly sketched. There are many sketch-books in the Tate Gallery in London, including those of Turner. Sketch-books are called "croquis" in French or "Pensieri" in Italian.