Plasmin is an enzyme in the body that plays a crucial role in breaking down blood clots. It is formed from its inactive precursor, plasminogen, which is activated during the process of fibrinolysis. This process helps to maintain normal blood flow and prevent excessive clotting. The activation of plasminogen to plasmin is triggered by various factors, including tissue plasminogen activator (tPA) and urokinase. Once activated, plasmin digests fibrin, the protein that forms the structure of blood clots, allowing the body to safely remove clots that are no longer needed.