In this book the authors present the basic formalism to describe the electromagnetic field and its interaction with nuclear matter. Among the areas studied are pion production, polarization phenomena, and photonuclear reactions at intermediate energies. At a time when data will become available from many newly commissioned laboratories both in Europe and the USA, this book offers a timely presentation of the current understanding of the electromagnetic response of atomic nuclei. Its introductory approach and rich bibliography will make it invaluable to postgraduate students and researchers.