The enigmatic journey of massive black holes, from the formation of a seed population in the early universe to their subsequent growth and mergers represents a vastly multi-scale phenomenon deeply intertwined with the process of galaxy formation. In this talk, I discuss the insights gleaned from cutting-edge cosmological simulations. These simulations not only provide some clues into the elusive population of Intermediate Mass Black Holes (IMBHs) but also shed light on some of the largest black holes in our Universe.

The main DESI redshift surveys have now collected 3 years of data and analysis of the Year-1 data set is almost complete. While concentrating  on the analysis of the Bright Galaxy Survey (BGS) in which I'm most directly involved  I plan to review the main cosmological results from other components of DESI. The BGS is a magnitude-limited (r<19.5) galaxy redshift survey and so rather like the SDSS main survey but about two magnitudes deeper. As such it is not only a useful cosmological probe but also a powerful probe of the local galaxy population and so a constraint on galaxy formation and the galaxy dark matter connection. I will present an analysis of how galaxy clustering depends on galaxyproperties and the galaxy luminosity function depends on environment.