A thrombus is a blood clot that forms in a blood vessel, obstructing blood flow. It can develop in arteries or veins and is often composed of platelets, red blood cells, and fibrin. Thrombi can lead to serious health issues, such as heart attacks or strokes, if they block blood supply to vital organs. Thrombus formation can occur due to various factors, including injury to a blood vessel, slow blood flow, or certain medical conditions. Risk factors include high blood pressure, diabetes, and prolonged immobility. Treatment may involve medications like anticoagulants to dissolve the clot and restore normal blood flow.