This book aims to provide a comprehensive and systematic understanding of research on extracellular vesicles (EVs). Extracellular vesicles, including exosomes and microvesicles, are nano-sized lipid bilayer encapsulated membranes carrying proteins, lipids, nucleic acids. They are shed by the majority of the cells into the extracellular milieu and present in many biological fluids (blood, urine, saliva, breast milk, cerebrospinal fluid, follicular fluid, semen, lung lavage, and tears). With numerous research publications in recent years, the study of EVs is the emerging field across plenty of disciplines. Many researches and efforts have shown their biogenesis, multiple roles in physiological and pathophysiological processes, and their potential roles as therapeutic agents. The book is organized by outstanding scientists in EV field from the Chinese Society for Extracellular Vesicle (CSEV). It covers the biological basic research of EVs, especially on technologies and methods, as well as the clinical application of EVs as biomarkers for disease diagnosis and therapy.