This document discusses different uses and benefits of sketching. It notes that sketching can be used for documentation, discovery, creative expression, and giving form to ideas. Sketching can also be used as a way of thinking and communicating ideas through illustration, description, and persuasion. The document emphasizes using quick, clear, and playful sketches that evolve ideas without overworking them. It lists different sketching techniques like linework, perspective, iterative sketching, exploratory sketching, and representative rendering. Movement and contour lines are also mentioned.