It's a good idea to sketch before you build a system. It's a good idea to sketch before you write a book. Sketching is a lightweight, low-fidelity way to get the ideas out of your head and onto paper. The act of sketching is the first step in designing anything. Sketching services are services that can help you get your ideas down.
A sketch is a drawing made to quickly capture the essence of a person, idea, place or thing. Sketches can be made in any drawing or painting medium, by using any of the techniques of drawing or painting. For example, sketches can be made in pencil, pen and ink, chalk, watercolour, art markers, collage, charcoal, or paint. The book has a collection of sketches from various artists.