The term for a group of stars is "star cluster." Star clusters are collections of stars that are gravitationally bound, and they can be broadly categorized into two types: open clusters and globular clusters. Open clusters consist of younger stars that are loosely bound and often contain a few hundred stars; they are typically found in the spiral arms of galaxies. Globular clusters, on the other hand, are densely packed with older stars and can contain tens of thousands to millions of stars. They are usually spherical in shape and orbit the centers of galaxies, providing insights into the formation and evolution of the universe.