Warfarin is a medication commonly used as an anticoagulant, which means it helps prevent blood clots from forming. It works by inhibiting the action of vitamin K, a nutrient essential for blood clotting. Patients often take warfarin to reduce the risk of stroke, especially those with conditions like atrial fibrillation or after certain surgeries. Monitoring is crucial while on warfarin, as its effectiveness can be influenced by diet, other medications, and individual health factors. Regular blood tests, known as INR tests, are performed to ensure that the blood's clotting ability remains within a safe range, minimizing the risk of bleeding or clotting complications.