Supercluster

[2] The large size and low density of superclusters means that they, unlike clusters, expand with the Hubble expansion.

Those groups and clusters and additional isolated galaxies in turn form even larger structures called superclusters.Their existence was first postulated by George Abell in his 1958 Abell catalogue of galaxy clusters.

[5] Superclusters form massive structures of galaxies, called "filaments", "supercluster complexes", "walls" or "sheets", that may span between several hundred million light-years to 10 billion light-years, covering more than 5% of the observable universe.

The directions of the rotational axes of galaxies within superclusters are studied by those who believe that they may give insight and information into the early formation process of galaxies in the history of the Universe.

[6] Interspersed among superclusters are large voids of space where few galaxies exist.