The Sun continually ejects matter into space, blowing a huge bubble of supersonic plasma. This solar wind bathes the whole solar system and shapes all planetary environments. The recent growth of space technology has considerably increased our knowledge of this medium. This book presents a modern introduction to the subject, starting with basic principles and including all the latest advances from space exploration and theory. It contains a short introduction to plasma physics and discusses the structure of the solar interior and atmosphere, the production of solar wind and its perturbations. It explains the objects of the Solar System, from dust to comets and planets, and their interaction with the solar wind. The final sections explore the astrophysical point of view. The topics are treated at various levels of difficulty both qualitatively and quantitatively. This book will appeal to graduate students and researchers in earth and atmospheric sciences, and astrophysics.