This open access book elucidates new biological phenomena caused by extracellular fine particles and highlights the development of base technologies for their control. In this book, the latest knowledge is collected on the principles of extracellular fine particles recognition, action, and biological responses. In addition, the base technologies for their detection, separation, measurement, and analysis are discussed. It also presents the treatment of endogenous and exogenous fine particles and analytical methods as well as functions of extracellular fine particles. This book is useful for undergraduate and graduate students engaged in research on extracellular fine particles, academic and corporate researchers, as well as national think tanks and national policy makers to understand the basics and applications of extracellular microparticles.