This is a textbook about cities or, more precisely, about the physical form of cities. It provides an overview of the main elements of urban form—streets, street blocks, plots and buildings—structuring our cities and the fundamental agents and processes of transformation shaping these elements. It applies this analytical framework to describe the evolution of cities over history as well as to explain the functioning of contemporary cities. After the initial focus on the object (cities), the book introduces how different schools of thought have been dealing with this object since the emergence of Urban Morphology, as the science of urban form, in the turning to the twentieth century. Finally, the book identifies the main contributions of urban morphology to cities, societies and economies. This second edition of the book offers updated and more accurate knowledge on several morphological issues, presents expanded contents, and it has a more explicit didactic nature, including a set of exercises in the end of each chapter, that will help teachers and students (in architecture, geography, planning, history, sociology and urban studies) in acquiring and consolidating their urban morphological knowledge.