  Stellar astrophysicists are increasingly taking into account the effects of
orbiting companions on stellar evolution. New discoveries, many thanks to
systematic time-domain surveys, have underlined the role of binary star
interactions in a range of astrophysical events, including some that were
previously interpreted as due uniquely to single stellar evolution. Here, we
review classical binary phenomena such as type Ia supernovae, and discuss new
phenomena such as intermediate luminosity transients, gravitational
wave-producing double black holes, or the interaction between stars and their
planets. Finally, we examine the reassessment of well-known phenomena in light
of interpretations that include both single and binary stars, for example
supernovae of type Ib and Ic or luminous blue variables. At the same time we
contextualise the new discoveries within the framework and nomenclature of the
corpus of knowledge on binary stellar evolution. The last decade has heralded
an era of revival in stellar astrophysics as the complexity of stellar
observations is increasingly interpreted with an interplay of single and binary
scenarios. The next decade, with the advent of massive projects such as the
Large Synoptic Survey Telescope, the Square Kilometre Array, the James Webb
Space Telescope and increasingly sophisticated computational methods, will see
the birth of an expanded framework of stellar evolution that will have
repercussions in many other areas of astrophysics such as galactic evolution
and nucleosynthesis.
