This thesis examines atrial fibrillation (AF) with a focus on its epidemiology, pathology, diagnosis, and treatment. AF prevalence rises with age with an increased incidence among men. Pathologically, atrial structural and electrical remodeling underlie arrhythmia development and persistence. Diagnosis is challenging, especially in asymptomatic or paroxysmal cases, and relies on tools like ECGand Holter monitoring. Treatment strategies include anticoagulation, rate and rhythm control, and procedural interventions, tailored to individual patient risks. This thesis highlights the complexity of AF and the need for careful clinical decision-making.