Alcohol use disorder (AUD) is a pervasive medical condition characterized by difficulty in controlling alcohol consumption despite adverse outcomes. This chapter addresses the epidemiology, etiology, neurobiology, diagnosis, clinical features, and comorbidities associated with AUD. The complexity of AUD is evident in its interaction with various biological, psychological, and social factors. This chapter aims to equip healthcare professionals with the knowledge needed to identify and diagnose AUD, ultimately improving patient outcomes.