The book aims to explain the variations of near-Earth plasma observed over seismically active areas several days/hours before strong seismic shocks. It demonstrates how seismo-ionospheric coupling is part of the global electric circuit and shows that the anomalous electric field appearing in active seismic areas is the main carrier of information from the earth into the ionosphere. The discussion of physical mechanisms is based on experimental data. The results can be regarded as the basis for future applications such as short-term earthquake prediction. It proceeds to describe existing complex systems of space-born and ground-based monitoring for electromagnetic and ionospheric precursors of earthquakes, as well as those still under construction. It is an excellent text for courses and contains a wealth of information for those scientists working in the field of natural disaster reduction.