The biomechanics of heart valves play a crucial role in their normal function and in the development of valvular heart diseases. This review explores the mechanical principles underlying normal heart valve function, the changes that occur in disease states, and how these alterations contribute to clinical manifestations of valve dysfunction. We discuss the impact of mechanical stress, strain, and fatigue on valve tissues, and highlight advances in imaging and computational modeling that have enhanced our understanding of valve biomechanics. The implications for diagnosis and treatment are also examined, with a focus on emerging technologies and therapeutic strategies.