This book mainly discusses the background of e-commerce, the basic knowledge of e-commerce, the basic models of e-commerce, the basic principles of e-commerce and the cases of e-commerce. This book has formed a theoretical system of e-commerce with a clear integration boundary. The introduction of the systematic theory is guided by the background of e-commerce, centered on the model of e-commerce, paved with the principles of e-commerce and integrated with the cutting-edge cases. This book defines the basic concepts, models and principle of e-commerce in the form of mathematical analysis and analyzes the basic theory of e-commerce from the perspective of mathematical model. This enables readers to form an abstract understanding of the connotation and extension of e-commerce. It establishes a knowledge system with the background of social ecology, engineering ecology and innovative ecology, taking the models of e-commerce as the core, the principles of e-commerce as the process, the architecture of e-commerce as the platform and the operation and management of e-commerce as the means to integrate the knowledge into application. This book uses case study to comprehensively analyze and apply the knowledge system involved in e-commerce, combining theoretical research with engineering research. Through this book, readers can systematically master all kinds of theories involved in e-commerce. This book aims at different professional and diverse reader groups. It can be used as the basic books for students of various e-commerce-related specialties.