Interstellar medium is the space between stars that is filled with gas and traces of dust.
Interstellar medium is a combination of carbon and silicates that are thinly spread in space.
This medium is a dynamic, ever-changing environment. It provides the cauldron from which stars are born. The continual energy flows through the ISM and the interchange of materials between its gas and that in stars forms a cycle that drives the evolution of galaxies.