Observations show that galaxies are distributed unevenly throughout the universe. Instead of all galaxies being about the same distance apart, the majority of galaxies are collected along vast filamentary and sheetlike structures many millions of light-years long. These filaments and sheets connect at dense nodes—clusters and super-clusters—of galaxies, and the net result is a three-dimensional, weblike distribution of matter in the universe nicknamed the Cosmic Web. Between the filaments and sheets are large pockets of space with relatively few galaxies; these sparse regions are called voids.