A fundamental part of this book is to introduce readers to the art of freehand sketching and the use of different media such as pencil, ink, and marker to communicate interior design concepts. It also discusses the principles of switching the left side of the brain to the right side of the brain as well as the principles of perceiving the objects by seeing negative space and positive space. Additionally, this book demonstrates a technique of transformation from traditional drawing to digital drawing that combines the characteristics of digital and freehand drawings.