Platelets were described over 150 years ago as small anucleate particles circulating in large numbers in the blood and clumping at sites of vascular injury to prevent blood loss. Progressively their morphology was revealed as microscopy became more powerful and their production by megakaryocytes in the bone marrow was revealed. The story of how the mechanisms behind their function were unravelled is both exciting and essential for cell biology. Early studies on platelet aggregation and adhesion were quickly followed by the discovery that surface glycoproteins mediated these processes, with many advances linked to studies on inherited bleeding disorders caused by defective platelet biogenesis and/or function. The finding that the same actors were responsible for both normal haemostasis and arterial thrombosis resulted in new treatments as has the understanding of the molecular basis of inherited and acquired thrombocytopenias. These success stories in medicine are just the beginning as current molecular biology and next-generation sequencing procedures result in the identification and role of a wide range of genes involved in platelet function and pathology. This has permitted the hope of refined medication and personalized medicine in the years to come.