Linked from
The 26 pages that link to Galaxy morphology, each with the reason it gives.
Galaxy evolutionRelated: Structural transformation is one visible outcome of galaxy evolution.
Galaxy interactionRelated: Mergers can transform orderly disks into more spheroidal remnants.
Interacting galaxyRelated: Tidal distortions can change the forms used to classify galaxies.
de Vaucouleurs's lawNarrower topic: The law grew from efforts to quantify galaxy structure.