Abstract details

Stellar population models are the key tool to derive the star formation history (age, chemical composition, etc.) and mass of (distant) galaxies. These properties in turn set important constraints to galaxy formation models. I shall discuss the impact of the assumed stellar population model and its prescriptions for the various stellar phases, on the derived properties of galaxies. To illustrate the case, I analyse various types of stellar systems from globular clusters to high-redshift galaxies. The results affect a number of recent findings like the redshift evolution of the mass size relation and of the black-hole mass - galaxy mass relation, as well as the discovery of very massive and old galaxies at very high redshifts.