Atrial fibrillation (AF) is the most common cardiac arrhythmia. AF reduces the patients' quality of life and increases the risks of heart failure, ischaemic stroke, and death. The aetiology of AF is complex and involves multiple pathophysiological pathways. Comorbidities often coexist in patients with AF and contribute to the pathogenesis. The pathogenesis, the most common comorbidities, and possible individualized treatment options of AF are discussed in this review.