Multiplicity and how it affects the evolution, fate, and influence of stars

Stars are the building blocks of galaxies and thus our visible Universe. Their formation is crucial forthe creation of planets and as they evolve their feedback (especially for higher mass stars) can givethem influence on their local environments and beyond. It is now known that stars across themass-range do not always live alone – many have a companion and exist in binary or potentiallyhigher order multiple systems. In this plenary, I will discuss how this multiplicity varies across differentstellar masses and how it can affect the evolution of the involved stars. As an example, I will alsopresent the results of the system HD148937, which illustrates the power that interactions in stellarmultiple systems can have on the stars involved through altering their properties, generatingmagnetism, creating ejecta and changing their fates.