Child marriage is a formal or informal union in which one or both parties are under the age of 18, often the legally recognized minimum age for marriage, although this threshold varies across jurisdictions. As an academic research concept and field of study, it examines the complex social, economic, legal, health, and cultural factors driving its occurrence, its diverse consequences for individuals and societies, and the efficacy of interventions and policy frameworks aimed at its eradication. Its significance is underscored by its profound implications for human rights, gender equality, poverty reduction, and the achievement of global development objectives.