This document summarizes the mechanisms of hemostasis (prevention of blood loss), including vascular constriction, platelet plug formation, blood clot formation, and fibrinolysis. It describes the clotting factors and roles of calcium and platelets. Methods for controlling hemorrhage are discussed, including mechanical methods like direct pressure, ligation, and cauterization, as well as chemical/biological agents and radiological interventions. Supportive measures like fluid resuscitation and blood transfusion are also recommended.