Galaxy clusters are large groups of galaxies that are bound together by gravity. They can contain anywhere from a few dozen to thousands of galaxies, along with hot gas and dark matter. These clusters are the largest known structures in the universe and can span millions of light-years across. The study of galaxy clusters helps astronomers understand the formation and evolution of the universe. By observing clusters, scientists can learn about the distribution of dark matter, the behavior of galaxies, and the effects of cosmic expansion. This research provides valuable insights into the fundamental forces shaping our cosmos.