Phenomena in space physics are complex and their understanding often requires the integration of different concepts of space physics. To help the beginner this book uses a new methodological approach. The first chapters introduce simple concepts of plasma physics and describe where these concepts can be applied in space physics. The subsequent chapters are devoted to more-complex observations. These are interpreted in terms of the concepts introduced earlier and new, more difficult, concepts are introduced where they are required. Thus observations and physical concepts can be interwoven to give basic explanations of phenomena and also show the limitations in these explanations and point out some rather fundamental questions.