Alcohol is one of the most widely consumed psychoactive drugs globally. Hazardous drinking, defined by quantity and frequency of consumption, is associated with acute and chronic morbidity. Alcohol use disorders (AUDs) are psychiatric syndromes characterized by impaired control over drinking and other symptoms. Contemporary aetiological perspectives on AUDs apply a biopsychosocial framework that emphasizes the interplay of genetics, neurobiology, psychology, and an individual's social and societal context. There is strong evidence that AUDs are genetically influenced, but with a complex polygenic architecture. Likewise, there is robust evidence for environmental influences, such as adverse childhood exposures and maladaptive developmental trajectories. Well-established biological and psychological determinants of AUDs include neuroadaptive changes following persistent use, differences in brain structure and function, and motivational determinants including overvaluation of alcohol reinforcement, acute effects of environmental triggers and stress, elevations in multiple facets of impulsivity, and lack of alternative reinforcers. Social factors include bidirectional roles of social networks and sociocultural influences, such as public health control strategies and social determinants of health. An array of evidence-based approaches for reducing alcohol harms are available, including screening, pharmacotherapies, psychological interventions and policy strategies, but are substantially underused. Priorities for the field include translating advances in basic biobehavioural research into novel clinical applications and, in turn, promoting widespread implementation of evidence-based clinical approaches in practice and health-care systems. Sections 0123456789();:Primer between countries 4 . Moreover, the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) and the 11th revision of the International Classification of Diseases (ICD-11) have substantively different categories for defining clinically meaningful alcohol involvement. The DSM-5 has one diagnosis (that is, AUD) with three levels of severity, whereas the ICD-11 has two diagnoses with escalating severity (that is, harmful pattern of use of alcohol followed by alcohol dependence) and also a subclinical designation of hazardous alcohol use that denotes a risk factor that has not reached the point of having caused harms to the person or others. Fundamentally, however, these clinical diagnoses reflect an inability to regulate alcohol consumption, and, although not formally designated as such, the more severe manifestations (severe AUD in DSM-5, alcohol dependence in ICD-11) are often considered the clinical equivalent of the colloquial term 'alcoholism' [5][6][7][8] .Given these definitional differences, this Primer primarily uses two terms for clarity. First, the term hazardous drinking is used to refer to drinking behaviour (such as per episode, daily or weekly) that reflect meaningful increases in risk of negative alcohol-related outcom...