Exosomes play an important role in intercellular communication by transferring substances such as proteins, lipids and nucleic acids between cells. The types and quantities of substances carried by exosomes vary depending on their cellular origin, resulting in heterogeneity in both the characteristics and functions of exosomes derived from different cell types. This heterogeneity underpins the basis of exosome function. Focusing on the heterogeneity of exosomes in terms of cellular origin and content, this article systematically elucidates the biological characteristics and functions of exosomes, providing a basis for future exosome screening and applications.