Hemostasis is an intrinsic property of the vascular system that prevents blood loss during accidental disruption of the vessel wall. Late mechanisms of hemostasis comprise vessel repair and wound healing. In contrast, the early mechanism of hemostasis comprises the quick formation of a blood cell plug, also known as thrombus, whose function is to seal the region of the vessel near the compromised surface or area. Despite the simplicity of the concept, the molecular mechanisms underlying early hemostasis are highly complex. The local rheological properties of the blood flow, the vascular region and the nature of the injury determine the mechanism of thrombogenesis. Components of the plasma, blood cells such as platelets and vascular endothelial cells are involved in thrombosis. This review focuses on platelet-vascular wall interactions during thrombosis and hemostasis and provides an overview of the main underlying molecular mechanisms.