MVs, which can be subgrouped into exosomes, SVs, and OMVs, are secreted by eukaryotic and prokaryotic cells. Many previously inexplicable phenomena can be explained by the existence of these vesicles, as they appear to be important in a wide range of biologic processes, such as intercellular communication and transfer of functional genetic information. In this review, the authors discuss the immunologic roles of MVs during sterile insult and infectious disease. MVs contribute to clotting initiation, cell recruitment, and neovascularization during wound healing. In the context of pathogen infection, both the host and the pathogen use MVs for communication and defense. MVs are exploited by various viruses to evade the host immune response and contribute to viral spread. Bacteria produce MVs that contain virulence factors that contribute to disease pathology and antibiotic resistance.