Hydroelectric dams are large structures built across rivers to harness the power of flowing water. They work by using the force of the water's movement to generate electricity, which can then be distributed through the electrical grid for use in homes and businesses. The water flows through turbines within the dam, spinning them and converting the kinetic energy of the water into mechanical energy. This mechanical energy is then converted into electrical energy by generators connected to the turbines. Hydroelectric dams are a renewable source of power, as they rely on the natural flow of rivers rather than depleting finite resources like fossil fuels. They can also provide other benefits such as flood control and recreational opportunities.