Institut de recherche sur les lois fondamentales de l'Univers

In the local universe, a star has a higher probability of being in a galaxy of the mass of the Milky Way than in any other galaxy, and we have the opportunity to be able to study one such galaxy from the inside. 

We can, in particular, study its stellar mass growth with time, and understand how each of the known stellar populations is connected to this mass growth history. 

While much is expected from the analysis of the Gaia data in this regard, it is safe to say that a change of paradigm concerning the stellar populations of our Galaxy is already under way, due in particular to important results coming from the analysis of recent spectroscopic surveys. I will present and discuss some of these results.