Exosomes refer to small membrane vesicles (30-150nm) containing complex RNA and proteins. In 1983, exosomes were first discovered in sheep reticulocytes. In 1987, Johnstone named it "exosome". A variety of cells can secrete exosomes under normal and pathological conditions, and exosomes naturally exist in body fluids, including blood, saliva, urine, cerebrospinal fluid, and milk. It is mainly derived from the multivesicular bodies formed by the invagination of intracellular lysosomal particles, which are released into the extracellular matrix after the fusion of the multivesicular outer membrane and the cell membrane. Exosomes are currently viewed as specifically secreted membrane vesicles involved in intercellular communication, and there is growing interest in the study of exosomes, both to study their function and to understand how they can be used in the development of minimally invasive diagnostics.