In the past couple of decades, there have been considerable advances in the efficiency, robustness and efficacy of inversion methods in almost every field. This is apparent in the many journal articles published on this subject, the ever-growing number of specialized sessions organized in major conferences, and in the several books and proceedings that have appeared in the past few years. Inverse scattering continues to be a primary area of research to a large number of scientists and practitioners. Many developments have been driven by several new applications and some old ones, such as mathematical physics, atmospheric sciences, geophysical prospecting, quantum mechanics, remote sensing, underwater acoustics, nondestructive testing and evaluation, medical imaging, to mention only a few. These developments have been applied to a variety of data that include direct current (DC), monochromatic, multi-frequency and transients. The majority of the effort has gone into improving on the robustness and speed of the various inversion techniques. A considerable effort has also gone into addressing the nonuniqueness and ill-conditioning that are inherent in almost all inverse scattering problems which arise mainly as a consequence of the inadequacy and redundancy in measurements. Many researchers have attempted to quantify these uncertainties by resorting to probabilistic methods. This special section is dedicated to the imaging and inversion of the Earth's subsurface by electromagnetic means with special emphasis, though nonexclusive, toward oil and mineral exploration, evaluation and monitoring.