Mills are the "factories" of Cargandom, putting yokes on wind or water to perform the work of many men. Mills are used for a variety of purposes - to full cloth, tan leather and to grind ore, but most importantly to grind grain into flour.
Any large village is likely to have a grain mill, on a windy hilltop or near a flowing stream.
Mills are noisy, dangerous places, with numerous pieces of rotating heavy machinery that can snag a man and kill or mangle him with uncaring strength. Furthermore, it is well known that gremlins roost eagerly in mechanical devices, so a mill is never truly safe.
Millers are usually well-to-do; They usually enjoy a monopoly, whether from practical reasons or enforced by the local liege. They have come to hold a position similar to that of blacksmiths, having unusual skills - apart from knowing how to run and repair a mill, a miller must also know how to ward it as much as possible from infestations of the aforementioned gremlins. These esoteric skills might presumably also be turned to evil uses...
Millers are often suspected of stealing flour from their customers' loads.
Invented by the Cargans, mills are a pinnacle of technology, culture harnessing raw nature. Ironically, it is also a loophole where chaos may find its way into the world