Invented by Adrian Bejan, the constructal theory of global optimization under local constraints explains in a simple manner the shapes that arise in nature. The theory is used to understand, calculate, and ultimately generate the irregular designs found in nature (trees, lightning, river deltas, etc.) and incorporate these designs in human-made systems to optimize the function of the system. Now, for the first time in a book, Bejan explains the concepts and applications of his theory, beginning with the basics and building to more and more complex systems for better student understanding.