Extracellular vesicles (EVs) are nanosized lipid bilayer particles that are produced by all kinds of organisms, including both pathogenic and non-pathogenic archaea, bacteria, fungi, and parasites. These vesicles serve as a means of cell-free intercellular communication, playing a variety of roles including in quorum sensing or tuning microenvironments to benefit the survival of microbes. Importantly in pathogens, EVs can modulate host immune responses to evade elimination from the host. Moreover, besides facilitating the survival of pathogens and acting as a decoy to chemotherapeutics as a drug resistance mechanism, microbial EVs have potential applications in the development of therapeutics and diagnostics for infectious diseases. Furthermore, EVs can be utilised as vaccine candidates, for drug targeting, and for RNAi communication vehicles, aside from their potential as biomarkers for disease diagnostics.