Windmill

A windmill is a machine operated by the force of wind acting on vanes or sails, historically built to mill grain rather than to generate electricity. The horizontal panemone type first appeared in Persia in the 9th century, and the vertical windmill familiar from European landscapes reached northwestern Europe by the 12th century. Internally, a windmill uses a system of gears to convert the rotating motion of its sails into mechanical work, historically used for grinding grain, pumping water and driving various industrial processes. The term is distinct from a wind pump, built specifically to move water, and from a modern wind turbine, which converts wind energy into electricity through a generator rather than driving machinery mechanically.