Extracellular vesicles (EVs) are membrane-encapsulated vesicles carrying various signal molecules, including metabolites, proteins, enzymes, genetic material, nucleic acids, mRNAs, noncoding RNAs, intact RNAs, lipids, organelles, ions, pathogenic microorganisms, and disease-specific molecules. The International Society for Extracellular Vesicles (ISEV) describes EVs as lipid-enveloped vesicles released from cells that do not contain a nucleus and cannot replicate themselves. EVs are categorized based on size and biogenesis as apoptotic bodies, exosomes, macrovesicles, and others. EVs are released from prokaryotic and eukaryotic cells, such as epithelial cells, mesenchymal stem cells, neurons, and endothelial cells, to regulate intracellular regulation and communication through blood circulation. Therefore, EVs are potential and promising biomarkers, drug delivery tools, and therapeutic approaches. These vesicles transfer knowledge of the parent cell’s biochemical and physiological status to the neighbor cells. The information of the neighbor cell from the current healthy or pathological conditions can be used not only for intercellular conditions but also as a biomarker for many biological or pathological processes. Crosstalk between the cells may have many crucial functions in health, aging-related disease, and cancer cell signaling. Delayed diagnosis and treatment lead to poor prognosis and increased risk for mortality in cancer patients; thus, novel cancer biomarkers are urgently required for early prognosis, disease progression monitoring, and personalized therapies. Since cell-cell interactions between tumor cells and cancer cell communication with stromal and immune cells occur via EVs, they are considered promising biomarkers for the early detection of cancer since they are secreted from cells circulating in the blood and are easy to collect. EVs have superior properties to overcome chemotherapy-related limitations because they have extended circulation time, excellent tumor-targeting capabilities, lower immunogenicity, higher biocompatibility, and reduced systemic toxicity in the peripheral tissues. In this chapter, we discussed the biogenesis, role, functions, and challenges of various types of EVs in aging-related diseases and cancer treatment.