Hydroelectric power generation is a method of producing electricity by using the energy of flowing water. Typically, a dam is built on a river to create a reservoir. When water is released from the reservoir, it flows through turbines, causing them to spin and generate electricity. This renewable energy source is considered environmentally friendly because it produces no direct emissions. However, the construction of dams can impact local ecosystems and communities. Overall, hydroelectric power is a significant contributor to the global energy supply, providing a reliable and sustainable alternative to fossil fuels.