The book is devoted to radio occultation (RO) remote sensing of the earth's atmosphere and ionosphere as a global method of monitoring. This technique used the radio links satellite-to-satellite when a satellite-receiver setting or rising behind the earth's atmosphere is relative to a satellite - emitter of radio waves. During setting the radio ray perigee moves through the ionosphere and ionosphere. Atmospheric and ionospheric effects arise in most cases owing to influence of a zone near the radio ray perigee and cause significant variations of the amplitude, phase, and frequency of the radio waves. These variations enable determination of the altitude profiles of temperature, pressure, refractivity, density, humidity and turbulence in the atmosphere, distribution of the electron density in the ionosphere, and the wave phenomena at different altitudes with a global coverage. The aim of this book consists of the systematic description of the different approaches, results of investigation and perspectives of the RO remote sensing as a tool for investigations of the atmosphere and ionosphere.