The ORBIT-AF registry is a multicenter prospective outpatient disease registry of patients with incident (initial diagnosis) or prevalent (existing diagnosis) atrial fibrillation (AF) that will analyze treatment patterns and outcomes in patients with AF in the US. Approximately 10,000 prospective cohort of patients will be enrolled. The registry will be a nation-wide collaboration of Health Care Providers (e.g., cardiologists, internists, primary care physicians, electrophysiologists, quality improvement personnel, office/practice managers, research coordinators, and pharmacists). This collaborative effort will be focused on the optimization of outpatient management of patients with AF. Consecutive patients who meet the eligibility criteria will be approached and educated about the registry. Patients who express interest will provide informed consent. Patients enrolled in the registry will be followed for approximately 3 years. Patient follow-up by their AF care provider will continue as scheduled according to local clinical practice. Patient Reported outcome (PRO) questionnaires will be administered to a sub-sample of approximately 1,500 patients. For patients who consent to answer PRO questionnaires, these questionnaires will be administered by the site to the patient at the baseline visit \[except the baseline Anticoagulation-Related Treatment Satisfaction (ACTS)\] and during their regularly scheduled follow-up visits. The baseline ACTS for incident patients will be completed and returned back to the site at least 4 weeks after starting antithrombotic therapies. The ACTS questionnaire will only be administered to patients who are taking antithrombotic therapies within the 4 weeks before a visit or newly prescribed antithrombotic therapies. Data collection will occur at 6-month intervals for a minimum of 3 years (baseline, 6 months, 12 months, 18 months, 24 months, 30 months, and 36 months). The data collection windows will be wide (3 months in either direction) in order to maximize data collection during the patients regularly scheduled follow-up with their AF care provider. Collection of Patient Reported Outcome (PRO) Questionnaires will not continue beyond the 24-month data collection interval. Atrial Fibrillation Data capture will include demographics, cardiovascular risk factors, diagnosis, type of AF (paroxysmal, persistent, permanent AF), treatment strategy (rate vs. rhythm), ablation history, cardioversions, antithrombotic therapy decisions and monitoring (INRs), concomitant medications and doses, insurance and provider information, AF quality-of-life, anticoagulation treatment satisfaction, caregiver assistance, pet ownership, comorbidities, compliance, and outcomes. Pre-defined outcomes of interest will include stroke or non-CNS (non-systemic) embolism, major adverse cardiac events, all-cause mortality, cause-specific death (sudden, non-sudden, heart failure-related), major bleeding, AF-related quality of life, anticoagulation-related treatment satisfaction, all-cause hospitalization and specific anticoagulation outcomes (e.g. time in therapeutic range and primary discontinuation of oral anticoagulation). The data generated by this registry will be used to identify real world practice, especially as it compares and relates to guidelines set forth by the American College of Cardiology, American Heart Association and European Society of Cardiology for the management of patients with AF. Observational Study - No investigational drug administered. For any patients receiving the sponsor's drug, Xarelto (rivaroxaban), under the direction of a physician, all serious adverse events and all non-serious related events will be reported to the sponsor (Janssen Scientific Affairs, LLC)