The intergalactic medium (IGM) is the matter that exists in the vast spaces between galaxies. It primarily consists of hydrogen and helium gas, along with trace amounts of heavier elements. This medium plays a crucial role in the formation and evolution of galaxies, as it provides the raw materials for star formation and influences the dynamics of galactic structures. In addition to gas, the IGM contains cosmic rays and dark matter, which are essential for understanding the universe's large-scale structure. The study of the intergalactic medium helps astronomers learn about the history of the universe and the processes that govern galaxy formation and evolution.