Before the polished mockup, before the pixel-perfect comp, there is usually a sketch. Quick, loose, often ugly. A sketch is a freehand drawing used to explore ideas without committing to them. It is thinking on paper.

Designers sketch for the same reason writers draft. The first idea is rarely the best one. Sketching lets you generate twenty variations in the time it would take to build one digital mockup. Most of them will be bad. That is the point. Bad sketches cost nothing. Bad finished designs cost a lot.

What sketches do well

• Generate many ideas fast
• Communicate rough concepts in meetings
• Expose layout problems before code gets written
• Keep the focus on structure, not surface

Architects sketch. Product designers sketch. Web designers sketch on paper, whiteboards, or tablets. Some keep sketchbooks the way musicians keep recordings, as a running record of half-formed ideas. A sketch is not a deliverable. It is a tool for thinking. The looseness is a feature, not a flaw. If a sketch looks too polished, people start critiquing the colors instead of the layout.