A sketch (ultimately from Ancient Greek σχέδιος - schedios "temporary"[1]) is a rapidly executed freehand drawing that is not intended as a finished work. If in oil paint it is called an oil sketch. In general, a sketch is a quick way to record an idea for later use. Artist's sketches primarily serve as a way to try out different ideas and establish a composition before undertaking a more finished work, especially when the finished work is expensive and time consuming (as in the case of a large painting or fresco). Sketching sharpens an artist's ability to focus on the most important elements of a subject and is a prescribed part of artistic development for students.
Dry media such as pencil or pastel are often preferred due to time constraints, but a quickly done watercolor study or even quickly modeled clay or soft wax can also be considered a 'sketch' in the broader sense of the term. Graphite pencils being a relatively new invention, the artists of the Renaissance could make sketches using the expensive method of a silver stylus on specially prepared paper (known as silverpoint), with results similar to a modern pencil sketch, or, more cheaply, using charcoal, chalk, or pen-and-ink.
