Houses with windmills are not all power houses. They are also used for grinding grain, coarse salt, tobacco leaves, pressing oil, rolling woolen cloth, felt, making paper and draining swamps. Standing water. A windmill is a power machine that does not require fuel and uses wind as energy. Early wind turbines were also called windmills. Modern wind turbines mostly refer to wind turbines used for power generation, and are also used to lift water for irrigation. Ancient windmills developed from sails. They had 6 to 8 sail-like canopies, distributed around a vertical axis. When the wind blew, they rotated around the axis like a revolving lantern. This was called a revolving windmill. Due to its low efficiency, this kind of windmill has been gradually replaced by wooden cloth windmills with horizontal rotating shafts and other windmills, such as vertical windmills, automatic rotor windmills, etc.