At the beginning of the chapter you can read that a supercluster of galaxies is named by grouping together neighbouring clusters whose morphology suggests a connection. But you will also see that to define a supercluster is even less practical than to define a cluster, given that a supercluster is generally not bound together by its internal gravity, and will tend to drift apart as time passes. Clusters and superclusters are named after the constellations towards which we see them, although they are at least a million times further away. There are two ways to pick out and image a supercluster, one using its imprint on the Cosmic Microwave Background Radiation, and the other using X-ray imaging, as described. Next we see how measuring the velocities of galaxies, groups, and clusters is used to plot their 3D positions in the universe. Using this, huge voids with hardly any galaxies were discovered between the superclusters, and then mapped. When the large scale structure of the Universe is mapped out this way the galaxies are found to lie concentrated in the walls of the voids. Two specific concentrations, Laniakea and The Great Attractor are mentioned in this context, as well as a recently discovered huge structure Quipu. New surveys to reveal large scale structure back to when the universe had only a fifth of its present age are explained. Theoretical models starting from the Big Bang, and containing dark matter and dark energy give a very fair explanation of the large scale structure, although they do less well in explaining the detailed properties of galaxies. New and more extended surveys, from both ground-based and space-based telescopes are under way, or in plan, to investigate the parameters of dark energy. Two of these already producing much data, DESI (ground based) and Euclid (satellite based) are described, as are two more advanced observatories, Vera Rubin (ground-based and operational) and Nancy Grace Roman (space-based and due for launch within 2 years).