Galaxy overdensities refer to regions within the universe where there is a higher than average concentration of galaxies compared to the overall distribution of galaxies in the universe. These overdensities can be an indication of large-scale structures such as galaxy clusters, filaments, and superclusters, which are some of the largest known structures in the universe. Studying galaxy overdensities can provide valuable insights into the formation and evolution of large-scale structures in the universe, as well as the role of gravity in shaping the distribution of galaxies. Researchers use various observational techniques, such as galaxy surveys and computational simulations, to study galaxy overdensities and their impact on the cosmic web.