What do we know?

• Early-type galaxies are mostly found in high density regions

• Luminous (massive) cluster E/S0 galaxies are redder (metal rich) – CMR relation

• Stars in Es are old but S0s can have younger populations

• … or could this be just a luminosity effect?

• The pops of spiral bulges are similar to Es (?)

• Field E/S0s are younger compared to cluster (?)