What is a thumbnail sketch?

A thumbnail sketch is a small, quick drawing or sketch that serves as a preliminary study or rough draft for a larger, more detailed artwork. It is typically done using loose, gestural lines and minimal detail to quickly capture the composition and overall design of the final piece. Thumbnail sketches are commonly used by artists to plan out compositions, explore different ideas, and work out the layout and proportions before starting on a more finished piece. They are a useful tool for brainstorming and visualizing concepts in a simple, quick manner. Thumbnail sketches are often done on a small scale, usually no larger than a few inches in size, and can be done using various drawing materials such as pencil, pen, or marker.