A large quasar group is a group of very bright, distant galaxies that are grouped together in space. The light from these galaxies is so bright that scientists can see them even though they are far, far away. Quasars are the brightest type of galaxy, and a large quasar group is an even bigger group of these bright galaxies. By studying large quasar groups, scientists can learn about how galaxies form and grow as groups over time.