Extracellular vesicles (EVs) are elements enfolded in a lipid bilayer membrane. Similar to exosomes, they are released by all living cells. They comprise a variety of bioactive molecules such as lipids, nucleic acids, metabolites and proteins. EVs have potential as a target for liquid biopsies because they can be detected in nearly all types of body fluids, including breast milk, blood, saliva, ascites and urine. Tumor-secreted EVs are important mediators for intercellular communication in both local and remote microenvironments. They are naturally taken up by the target cells and could be utilized to transfer therapeutic agents. It is crucial to recognize EV subtypes in order to determine which pathways are influenced by EVs and which subtypes can be targeted in liquid biopsies or therapeutic methods. This book provides comprehensive insights on extracellular vesicles. It is compiled in such a manner, that it will provide an in-depth knowledge about the role of extracellular vesicles in human health. This book will serve as a reference to a broad spectrum of readers.