The organised efforts of governments, health systems, and communities to prevent substance-related harms, promote wellbeing, and improve population health outcomes. A public health approach focuses on prevention, early intervention, treatment, recovery support, and harm reduction, while also addressing the social, economic, and environmental factors that influence substance use. It relies on surveillance data, evidence-based interventions, policies, and cross-sector collaboration to reduce the overall burden of substance use disorders and promote healthier communities.