Platelet-derived extracellular vesicles (pEV) are heterogeneous subcellular structures released by platelets upon activation or apoptosis, playing diverse roles in physiological and pathological processes. pEV are the most abundant extracellular vesicles in circulation, transporting bioactive molecules, including clotting factors, cytokines, and nucleic acids. They are implicated in hemostasis, inflammation, immunity, tissue repair, and cancer. pEV biogenesis occur through two main mechanisms: endosomal pathways, generating exosomes, and plasma membrane budding, producing microvesicles. Their content and function depend on the activating stimuli and pathological context. They contribute to coagulation via phosphatidylserine exposure and thrombin generation, regulate inflammation by modulating immune cells through cytokine and microRNA transfer, and enhance tissue regeneration by delivering growth factors. Paradoxically, they display pro- and anti-inflammatory properties, reflecting their complexity. pEV can also influence cancer progression through tumor cell signaling and angiogenesis. Detecting and characterizing pEV remain challenging due to their heterogeneity and small size. Methods include high-sensitivity flow cytometry and imaging, nanoparticle tracking analysis, or functional assays. Standardized protocols such as those recommended by the International Society for Extracellular Vesicles are essential to ensure reproducibility of clinical studies. pEV levels and molecular cargo serve as emerging biomarkers for various diseases, including cardiovascular disease, cancer, infections, and autoimmune disorders. Advances in understanding pEV biology and functions offer promising avenues for clinical applications in disease monitoring and treatment.