A "supercluster" is a large group of galaxies that are bound together by gravity. These massive structures can contain hundreds or even thousands of galaxies, along with gas and dark matter. Superclusters are among the largest known structures in the universe and can span hundreds of millions of light-years. One well-known example of a supercluster is the Laniakea Supercluster, which includes our own Milky Way Galaxy. Superclusters are important for understanding the large-scale structure of the universe and how galaxies interact and evolve over time.