This will be a major arena of work in the next few years. It will be possible to search for low mass components of the haloes of M31 and M33 by microlensing. This will provide a direct comparison with the results for our own galaxy halo now being accumulated, and relate to galaxy formation and history. There are studies of the outer stellar and cluster populations in galaxies and clusters of galaxies. These trace the history of star-formation and merging of galaxies.
Current results show great promise but lack statistics of sufficient numbers.
Dust content of galaxies by measuring background galaxies. The study of diffuse stellar populations is another aspect of understanding star-formation processes and their effects on galaxy histories. Topics 1-7 are all under the subject area of understanding how stars make up galaxies and affect their behaviour. It will be a very active area over the next few years. These studes will seek to understand the history and workings of galaxy clusters, which are the largest bound systems known, and probably the oldest.