Exosomes are small membrane vesicles secreted by most cell types, initially described in 1983. Interest in exosomes has surged in recent years due to the discovery that they contain mRNA and microRNA, leading to increased research on their composition, function, and potential as biomarkers. Exosomes were once considered mere cellular waste but are now recognized as signaling payloads containing specific proteins, lipids, and genetic material that can alter the function and physiology of recipient cells. The field of exosome research has expanded rapidly, with nearly 350 studies published in the last three years alone. Exosomes are formed in endosomal compartments and released upon fusion with the plasma membrane. They can be purified by size-based methods, but other types of membrane vesicles, such as microvesicles and ectosomes, also exist and may have distinct functions. RNA, including mRNA and microRNA, has been identified in exosomes, suggesting their role in intercellular communication. Exosomes have been shown to induce various physiological changes in recipient cells, particularly in the immune system, where they can promote or suppress immune responses. However, the physiological functions of exosomes in vivo remain unclear, and further research is needed to understand their roles in different physiological contexts. The International Workshop on Exosomes (IWE) in Paris brought together researchers to discuss recent findings and challenges in the field, leading to the decision to establish future annual meetings and a scientific society dedicated to exosomes and secreted membrane vesicles.Exosomes are small membrane vesicles secreted by most cell types, initially described in 1983. Interest in exosomes has surged in recent years due to the discovery that they contain mRNA and microRNA, leading to increased research on their composition, function, and potential as biomarkers. Exosomes were once considered mere cellular waste but are now recognized as signaling payloads containing specific proteins, lipids, and genetic material that can alter the function and physiology of recipient cells. The field of exosome research has expanded rapidly, with nearly 350 studies published in the last three years alone. Exosomes are formed in endosomal compartments and released upon fusion with the plasma membrane. They can be purified by size-based methods, but other types of membrane vesicles, such as microvesicles and ectosomes, also exist and may have distinct functions. RNA, including mRNA and microRNA, has been identified in exosomes, suggesting their role in intercellular communication. Exosomes have been shown to induce various physiological changes in recipient cells, particularly in the immune system, where they can promote or suppress immune responses. However, the physiological functions of exosomes in vivo remain unclear, and further research is needed to understand their roles in different physiological contexts. The International Workshop on Exosomes (IWE) in Paris brought together researchers to discuss recent findings and challenges in the field, leading to the decision to establish future annual meetings and a scientific society dedicated to exosomes and secreted membrane vesicles.