Medieval peasants grew corn, just as we do today. The grain was ground into flour, used for baking bread. Every farmer had his own hand-mill, often used during the autumn. In the 12th, 13th and 14th centuries, cultivation increased and there was more grain to be ground. Where many people lived, one built water-mills or wind-mills. The wind-mills were used on the windy coasts, and the water-mills in the interior of the country. The water mills were built by the waterfalls in the streams and rivers. The running water made the mill-wheel turn, and the wheel made the mill-stones grind.
A person who owned land by a waterfall had the right to build a mill if it did not stop the flow of water to another, older mill. Some people took advantage of this right and became full-time millers. At the mills, neighbouring peasants paid a fee to have their grain ground. Sometimes, a few peasants built a mill together and took turns in using it.
In the Middle Ages, a lot of land was owned by the Church or the nobility. A mill could not be built on their land without special permission. The Church and the nobility were allowed to build mills on their own land. They could then make the peasants take their corn there and pay for having it ground. There were probably peasants who secretly built a little mill at a stream in the wood which the noblemen knew nothing about.