This revised edition describes our current understanding of the sun -- from its deepest interior, via the layers of the directly observable atmosphere to the solar wind, right up to its farthest extension into interstellar space. It includes a comprehensive account of the history of solar astrophysics and space weather, along with an overview of the key instruments used throughout the various periods. In contrast to other books on the subject, the choice of material deals evenly with the entire scope of important topics covered in solar research, elucidating the advances in our understanding of the sun by the careful use of relatively simple physical concepts. The result is an incisive, reliable, and well-planned look at all that is fascinating and new in studies of the sun for students and non-specialists.