Electric currents and electromagnetic fields have been applied to biological systems, particularly humans, with both therapeutic and pathological results. This text discusses biological responses to electric currents and electromagnetic fields, including medical applications and shock hazards. It covers fundamental physical and engineering principles of responses to short-term electrical exposure and emphasises human reactions, although animal responses are considered as well, and the treatment covers reactions from the just-detectable to the clearly detrimental. An important new chapter discusses standards for human exposure to electromagnetic fields and electric current and demonstrates how these standards have been developed using the principles treated in earlier chapters.