Recent advances in observations and modelling of solar and stellar flares have opened up new perspectives for understanding the fundamental physical mechanisms of magnetic energy storage and release, particle acceleration, and their radiative and dynamical processes. New interest in this topic is stimulated by Kepler observations and the discovery of superflares on solar-type stars, which raises questions about the possibility of such flares on the Sun, and the potential effects of superflares on terrestrial and extraterrestrial planets, including their impact on the origin and evolution of life. IAU Symposium 320 discusses the recent advances in observations and theories of solar and stellar flares, focusing on the understanding of their phenomenological and physical aspects, as well as consequences for terrestrial planets and exoplanets. This volume will be useful to researchers of all levels working in this fascinating and rapidly developing field of astronomy.