Book excerpt: This is the first book to give a comprehensive overview of recent observational and theoretical results on solar wind structures and fluctuations and magnetohydrodynamic waves and turbulence, preference being given to phenomena in the inner heliosphere. Emphasis is placed on the progress made in the past decade in the understanding of the nature and origin of especially small-scale, compressible and incompressible fluctuations. Turbulence models describing the spatial transport and spectral transfer of the fluctuations in the inner heliosphere are discussed. Intermittency of solar wind fluctuations and their statistical distributions are investigated. Studies of the heating and acceleration effects of the turbulence on the background wind are critically surveyed. Finally, open questions concerning the origin, nature and evolution of the fluctuations are listed, and perspectives for future research are outlined. The book is for graduate students and researchers in the field. Other target groups are scientists and professionals interested in space plasma physics and/or MHD turbulence.