Perturbations of electric and magnetic fields with periods of the order of 1 second are commonly observed in the auroral region by satellites and sounding rockets. The events are often accompanied by magnetic field aligned electron precipitation. The observations have been interpreted as inertial Alfve´n mode waves. A variety of theories, some of which are surveyed here, have been suggested to describe such events. Recent observations of Alfve´nic activity by sounding rockets and satellites are presented and their implications for the theoretical models are discussed. ©2000 American Institute of Physics.