Windmills are structures that convert wind energy into mechanical power. They typically have large blades that rotate when the wind blows, turning a central shaft. This movement can be used for various purposes, such as grinding grain or pumping water. Modern windmills, often referred to as wind turbines, generate electricity by using the same principle. The rotating blades turn a generator, producing power that can be supplied to homes and businesses. Windmills have been used for centuries and are an important part of renewable energy efforts today.