Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with multiple adverse events that increase morbidity and mortality, such as heart failure, systemic embolism, ischemic stroke, cerebrovascular accidents and sudden death. The prevalence of AF patients is now increasing worldwide regarding to the increasing aging population with improved multiple comorbidities treatment. The mechanisms and pathogenesis of AF are complex and still unclear. Recently, there have been multiple debates regarding what best treatments are suitable for individual AF patients. A better understanding of the pathophysiology of AF will help to decide the best strategy for each individual, which will impact the treatment of AF substantially and, more importantly, decrease the socioeconomic burden caused by AF. This book will provide the latest updates on atrial fibrillation, pathophysiology, classification, new guidelines and technologies, including advances and current antiarrhythmic drugs, catheter ablation, surgical ablation, left atrial appendage device closures and future direction of atrial fibrillation treatments.