The purpose of this monograph is both to introduce and review developed tomograhic methods for discovering 2D and 3D structures of the ionosphere and to discuss the experimental implementation of these methods. The theoretical part deals with the solution of the inverse problem of diffraction tomography for a wide range of properties of ionospheric media. Examples are given to illustrate the experimental reconstruction of electron-density distributions in ionospheric sections. In addition to addressing the specialist researcher, the detailed derivations and explanations make this book an excellent starting point for nonspecialists and graduate students who wish to enter this exciting new field to which the authors have made pioneering contributions.