A thumbnail sketch is a visualization tool that helps you plan your artwork. Thumbnail sketches help us capture the essence or the nature of the subject and plan the composition of our piece. These sketches are small, general 2 or 3 inches and not intended to be a finished sketch. Usually the first sketch is not the best and will not be used. Thumbnails take practice, and will become more useful as the artists works with them. Sometimes I refer to them as quick sketches or planning sketches.