A collection of stars is termed a "star cluster." Star clusters are groups of stars that are gravitationally bound and can be categorized into two main types: open clusters and globular clusters. Open clusters are loose groups of young stars, often found in the arms of spiral galaxies, while globular clusters consist of tightly packed old stars, typically located in the halos of galaxies. Studying these clusters helps astronomers understand stellar evolution, formation, and the overall structure of galaxies. Each type of cluster provides valuable insights into the life cycles of stars and the dynamics of the universe.