Abstract Atrial fibrillation (AF) is the most common cardiac arrhythmia encountered in clinical practice. Because of inadequate efficacy of pharmacological therapy, catheter ablation of AF has evolved dramatically over the last decade. Although the success rate of ablation has improved, the ablation strategy is still extensive, and the ablation procedure is technically challenging. In the past decade, electrophysiologists were eager to obtain high success rates with extensive ablation. In the present decade, further clarification of the complex mechanism of AF is required to make ablation of AF safer and much more efficient. Because the mechanism of AF is very complex, and even somewhat mysterious, it may not be easy to attain a better understanding of the mechanism involved or to discover better guidance for catheter ablation. However, it is important to note that research into AF leads to better understanding of other cardiac and non-cardiac diseases because AF develops multifactorially in association with underlying systemic pathophysiologies.