Systematically collected information used to understand patterns of substance use, substance use disorders, treatment needs, and drug market dynamics. This may include epidemiological data, service utilisation records, treatment outcomes, law enforcement intelligence, and public health surveillance. Data helps identify emerging trends, assess the effectiveness of prevention and treatment programmes, monitor trafficking and market activity, and guide evidence-informed policy and decision-making. Reliable data systems are essential for improving responses to substance use and ensuring that interventions are targeted, effective, and responsive to population needs.