Windmills have been in existence for over 800 years and although only a fraction of those that once ground corn, pumped water and provided power for industry and agriculture, now survive. Among the most important features of these survivors are the variations in design that have come about through their different origins, the use of local materials in their construction, and the influence of millwrights and millers - those who built and worked them - in different parts of the country. Understanding these variations provides important clues to the need to protect and maintain windmills, the continued survival of which allows a fascinating insight into the historic use of renewable energy, the development of engineering, and the processing of grain, for flour and bread, as well as other essential products.