Interstellar matter refers to the gas, dust, and other material that exists between stars within a galaxy. This material plays a crucial role in the formation and evolution of stars and planetary systems. Interstellar matter can be in various forms, such as molecular clouds, diffuse gas, and dust grains. Studying interstellar matter can provide insights into the physical processes that govern star formation, the chemical composition of galaxies, and the overall structure and dynamics of the universe. Researchers often use a range of observational techniques, such as radio astronomy and infrared spectroscopy, to study interstellar matter and its properties.