This document summarizes key concepts from the book Cradle to Cradle. It discusses moving from a cradle to grave model, where products are used then thrown away creating waste, to a model where waste is designed to be food for something new. It introduces the concepts of technical and biological nutrients, where technical nutrients can be reused infinitely and biological nutrients contribute nutrients back to the natural world. Examples given include edible utensils that can be thrown away without guilt and renting shoes where the upper material biodegrades while the sole is reused. A 5 step process is outlined to get free of known toxins and follow informed preferences to reinvent systems using safe materials in a circular flow.