There is a world of untapped energy within easy reach of human beings; a world abounding in wind energy. The book introduces the reader to this non-conventional resource of energy, covering it growth since the olden days to the present, the evolution of windmills, their design variations, their basic theory, etc., besides highlighting the fact that wind energy can be converted into mechanical and electrical energy by windmills. This small volume written in lucid language will be useful to the layman, the expert and those interested in harnessing the wind for providing energy.