Stellar populations are one of the most powerful tools we have to investigate the formation and evolution of galaxies. In our own Milky Way, stellar populations of thin and the thick disk, the bulge and halo, the globular and open clusters, the dwarf satellites and the stellar streams, all have locked within them the "fossil record" of their formation; measuring their ages allows us to look back through cosmic time, to an age when precursors objects can be directly observed and studied in deep fields. The same is true for galaxies in the Local Group, whose stellar populations can be resolved, age-dated and chemically analysed. Resolved stellar populations also allow us to verify and calibrate synthetic stellar population tools which can be used to study more distant galaxies in integrated light, and thereby estimate their ages, stellar masses, star formation rates, and metallicities all of which is essential information to understand the formation and evolution of galaxies.
In recent years rapid progress has been made on all fronts, in part due to the latest generation of telescopes on the ground and in space but also to continuous refinements of stellar population models. International teams have combined the unique capabilities of one telescope with those of another to make significant advances: for example, the wide field-of-view of Subaru prime focus instruments such as Suprime-Cam FMOS combined with the high multiplex of the VIMOS optical multi-object spectrograph and integral field unit spectrograph SINFONI at ESO's Very Large Telescope.
With the avalanche of data arriving from these new state-of-the art instruments on large telscopes it is time to re-consider critically all aspects of stellar populations in nearby and distant galaxies. Furthermore, stellar populations provide us with powerful tools to measure the size and content of the Universe and probe the evolution of baryons in dark matter structures. In the next decade, several key tests of our current cosmological model with be made with billion-galaxy surveys, and the results and successful exploitation of these surveys will depend critically on a profound undetanding of stellar populations both near and far. Our conference aims to further international cooperation for the best use of all available tools to advance our understanding. Prof. Nobuo Arimoto, of the National Astronomical Observatory of Japan, has played an important role in fostering such cooperation. In celebration of his 60th birthday, our conference is dedicated to him. This conference is also recognized as the 4th of the Subaru International Conference Series.