What is the component of blood that clots and seals cuts in your skin?

The component of blood that clots and seals cuts in your skin is called fibrin. Fibrin is a fibrous, insoluble protein that forms when soluble fibrinogen is converted by the action of thrombin. Fibrin forms a meshwork of strands that traps platelets and red blood cells, creating a blood clot that plugs the damaged blood vessel and stops bleeding.