The variable activity of stars such as the Sun is mediated through stellar magnetic fields, radiative and energetic particle fluxes, stellar winds and magnetic storms manifested as stellar flares and coronal mass ejections. This activity influences planetary atmospheres, climate and habitability: on the one hand it drives life-sustaining processes on planets, but on the other hand can adversely impact planetary environments rendering them uninhabitable. Studies of this intimate relationship between the parent star, its astrosphere and the planets that it hosts have reached a certain level of maturity in our own Solar System. Based on this understanding, the first attempts are being made to characterize the interactions between distant stars and their planets and understand their coupled evolution, which is relevant for the search for habitable exoplanets. IAU Symposium 328 brings together diverse, interdisciplinary reviews and research papers which address the themes of star–planet interactions and habitability.