Bulge/Disk Segregation in the Universe

The observations of bulge/disk segregation in the Universe are reviewed with a focus on whether the observed segregation in clusters is local or global, and whether there is bulge-disk segregation on large-scales. The high concentration of bulge-rich galaxies in the cores of clusters of galaxies can be accounted for by several popular physical processes: 1) biased early elliptical formation, 2) abortion of disk formation by tidal destruction of the gas reservoirs that fuel such disks, 3) ram pressure stripping of the gas in disks by intergalactic gas, 4) merging of spiral galaxies into ellipticals (which is the main focus of this review). A global scenario is outlined incorporating each of these processes.