windmills

Windmills are machines that use wind power to perform work. Historically they were used to grind grain, crush seeds, and pump water, while modern wind turbines convert wind energy into electricity.

Most traditional windmills consist of sails attached to a rotating windshaft. When wind turns the sails, a gear train drives millstones or pumps. The cap or top of the mill often rotates to keep the sails facing the wind, controlled by a tail vane or fantail in some designs.

Origins of wind-powered mills date to early medieval times in regions such as Persia and China, but the Netherlands developed sophisticated forms including the post mill and the tower mill to drain polders and mill grain. Windmills spread across Europe and beyond, becoming important rural technologies and symbols in many communities.

Two broad categories persist: those used for mechanical work (grinding, lifting, pumping) and those designed to generate electricity. Traditional designs include Dutch tower mills, post mills, and smock mills, with sails that can be adjusted or automated to varying wind conditions. Modern wind turbines, by contrast, employ a horizontal axis with usually three blades mounted on a tall tower and are a major source of renewable energy worldwide.