Several members of our group are involved in the astrometric space mission Gaia (ESA) launched end of 2013. Gaia is a key mission for undertstanding how stars and our Milky Way has been formed. We are in particular interested in charcacterising the chemical properties of stars using high-resolution spectra. With Gaia a dynamical map (positions, proper motions, radial velocities, distances) and a chemical one (chemical abundances, stellar parameters) of stars in our Milky Way will be obtained. This allows us to better unerstand the process of the Galaxy formation and evolution. Our Milky Way can in this respect be used as "calibration" Galaxy in terms of Galaxy formation and evolution