Metallicities refer to the abundance of elements heavier than hydrogen and helium in a star or galaxy. These elements, also known as metals in astrophysics, play a crucial role in the formation and evolution of celestial bodies by influencing their physical and chemical properties. Studying metallicities can help astronomers understand the history of star formation, the composition of galaxies, and the processes that drive the evolution of the universe. This research area often involves measuring the abundance of specific elements in celestial objects using spectroscopic techniques and modeling the chemical evolution of galaxies over cosmic time.