The space environment of a star and its planetary system encompasses the physical conditions and processes that shape the regions in which planets reside. This environment is driven by stellar particle and photon radiation, including stellar winds, extreme ultraviolet (XUV) radiation, coronal mass ejections (CMEs), stellar flares, and stellar energetic particles (SEPs). These phenomena can influence both the formation and long-term evolution of planets, particularly smaller, terrestrial worlds. With the exception of stellar flares, most of these processes cannot be directly observed in a consistent and comprehensive manner in distant planetary systems. Consequently, our understanding of their impact on exoplanets relies heavily on extrapolating knowledge gained from the Sun and the solar system to more extreme stellar and planetary environments, especially those hosting close-in planets around M-dwarf stars. In this talk, I will review the ways in which the space environment can affect terrestrial exoplanets and their atmospheres. I will discuss how insights from our own solar system provide a critical framework for understanding the evolution, atmospheric retention, and potential habitability of planets orbiting other stars.
