A post mill is a type of windmill that has a rotating structure mounted on a single vertical post. This design allows the entire mill to turn to face the wind, optimizing its efficiency in harnessing wind energy. The main components include the body, or "buck," which houses the milling machinery, and the sails that capture the wind. Post mills were commonly used in Europe from the Middle Ages until the 19th century. They are often found in rural areas and are considered an important part of the history of agriculture and industrial technology. Today, many post mills have been preserved as historical landmarks.