Hydropower is the interdisciplinary academic field and technological practice focused on harnessing the kinetic and potential energy of water for power generation. It investigates the fundamental principles of hydrodynamics and energy conversion, the engineering design and optimization of hydraulic structures and turbomachinery, and the comprehensive environmental, social, and economic implications associated with the development and operation of hydro energy systems. This field is characterized by its reliance on the hydrological cycle as a renewable resource and its significance in providing a substantial source of dispatchable renewable energy, contributing to grid stability, water management, and research into sustainable energy transitions.