A giant molecular cloud is a massive cloud of interstellar gas and dust that is primarily made up of molecules. These clouds are found in regions with active star formation and can span several hundred light-years in size. Synonyms for giant molecular clouds include GMCs, molecular clouds, molecular cloud complexes, and molecular cloud cores. GMCs play a crucial role in the formation of stars and planets, as they provide the raw materials necessary for these celestial bodies to form. Despite their size and importance, these clouds can be difficult to observe due to their high levels of dust and gas. However, astronomers continue to study these clouds to deepen their understanding of star formation in the universe.