The ORBIT-AF registry will be a multicenter, prospective outpatient disease registry to identify "real world" treatment patterns of atrial fibrillation. The registry will describe this patient population with regards to demographics, clinical factors, risk stratification, and geographic regions. In particular, attention will be focused on the utilization, effectiveness, and safety of antithrombotic therapies in the prevention of stroke. The registry is designed to identify reasons and risk factors for non-receipt of anticoagulation (AC) therapy, as well as reasons why AF patients who are prescribed AC therapy do not take them.