A sketch (ultimately from Greek σχέδιος – schedios, "done extempore") is a rapidly executed freehand drawing that is not usually intended as a finished work. A sketch may serve 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 principal. Sketching is generally a prescribed part of the studies of art students.

The term "sketch" has most often been applied to graphic work executed in a dry media such as graphite pencil, charcoal or pastel. It may also apply to drawings executed in pen and ink, ballpoint 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 or plasticine.

The term "sketchbook" refers to a book of blank paper on which an artist can, (or has already) drawn sketches. The book might be purchased bound or might comprise loose leaves of sketches assembled or bound together.

Most visual artists use, to a greater or lesser degree, the sketch as a method of recording or working out ideas. The sketches of some individual artists have become very well known, including those of Leonardo da Vinci and Edgar Degas which have become art objects in their own right, with many pages showing finished studies as well as sketches.