Clusters of galaxies are large-scale structures in the universe that consist of a group of galaxies bound together by gravity. These clusters can contain anywhere from a few dozen to thousands of galaxies, along with hot gas and dark matter, forming the largest known gravitationally-bound structures in the universe. They are essential for understanding the distribution of matter and the evolution of cosmic structures over time.
congrats on reading the definition of Clusters of galaxies. now let's actually learn it.