A leading stellar astronomer summarizes our understanding of supernovae and their interaction with interstellar gas, including the ambient interstellar medium, the gas ejected in the explosion itself, and the gas emitted as stellar wind. She examines the evolution of supernova remnants as they interact with the gas and considers the role of supernovae and stellar wind in the physical state of the interstellar medium. Essential reading for specialists in supernovae and stellar evolution.