Each chapter deals with a different technique from which we can best represent and make explicit the forms of knowledge used by designers. The book explores whether design knowledge is special, and attempts to get to the root of where design knowledge comes from. Crucially, it focuses on how designers use drawings in communicating their ideas and how they `converse' with them as their designs develop. It also shows how experienced designers use knowledge differently to novices suggesting that design `expertise' can be developed. Overall, this book builds a layout of the kinds of skill, knowledge and understanding that make up what we call designing.