Coagulation or clotting is the last hemostasis phase. It involves a series of chemical reactions to form a blood clot, reinforcing the initial platelet plug. The clotting process is a cascade of extrinsic, intrinsic, and common pathway reactions involving procoagulants or clotting factors. The extrinsic and intrinsic pathway reactions result in the formation of an activated complex called the prothrombin activator. The prothrombin activator facilitates the conversion of prothrombin into thrombin in the blood for the downstream reactions of the common pathway. Once activated, thrombin protein acts as an enzyme, converting fibrinogen in the blood into insoluble fibrin. These fibers polymerize to form a mesh-like structure that captures blood cells, platelets, and plasma. Also, the fibrin fibers stick to damaged surfaces of blood vessels, creating a blood clot. Typically, under 3 to 6 minutes, the clot can fill the vascular wound, permanently sealing the injury.