Blood coagulation is the process by which blood changes from a liquid to a gel, forming a blood clot. This process is essential for stopping bleeding when injuries occur. It involves a series of complex biochemical reactions that activate specific proteins in the blood, known as clotting factors, which work together to form a stable clot. The coagulation process begins with the constriction of blood vessels and the activation of platelets, which are small cell fragments in the blood. These platelets adhere to the site of injury and release chemicals that attract more platelets. Eventually, a mesh of fibrin, a protein formed from fibrinogen, stabilizes the clot, sealing the wound and preventing further blood loss.