Exposure of cells and tissues to electric fields can lead to a variety of physiological changes. These changes are caused by the interactions between the incident field and biological, chemical and electric (magnetic) processes. Evaluating whether the physiological changes are beneficial or harmful to the functionality of cells and tissues requires understanding the nature of the interactions, which can be associated with either thermal or non-thermal (bio)-effects. Although a considerable amount of research worldwide has shed light on these effects and their influence in the biological response, much more is left to say about the possible interaction mechanisms and the underlying biological processes modified by the incident field. In fact, the adequate conditions of exposure (dosimetry) needed for cells and tissues to trigger a certain positive response and avoid possible damage are still a matter of debate. Moreover, concerns coming from social sectors about the hazards of the exposure have motivated multiple studies that have yielded controversial results.