Hydropower is a form of renewable energy that harnesses the energy of flowing or falling water to generate electricity. It is one of the oldest and most widely used sources of energy, providing a significant portion of the world's electricity. Hydropower plants convert the kinetic energy of water into mechanical energy, which is then transformed into electrical energy through turbines and generators. This energy source is considered environmentally friendly as it produces no direct emissions. However, the construction of large dams can impact local ecosystems and communities. Overall, hydropower plays a crucial role in the transition to sustainable energy systems.