Hydroelectric dams are structures built across rivers to generate electricity by harnessing the power of flowing water. When water is released from a reservoir created by the dam, it flows through turbines, causing them to spin. This spinning motion converts the kinetic energy of the water into mechanical energy, which is then transformed into electrical energy by generators. These dams not only produce renewable energy but also help with flood control and water supply management. By regulating river flow, hydroelectric dams can provide water for irrigation and drinking, supporting both agriculture and communities.