  Massive black holes (MBHs) are nowadays recognized as integral parts of
galaxy evolution. Both the approximate proportionality between MBH and galaxy
mass, and the expected importance of feedback from active MBHs in regulating
star formation in their host galaxies point to a strong interplay between MBHs
and galaxies. MBHs must form in the first galaxies and be fed by gas in these
galaxies, with continuous or intermittent inflows that, at times, can be larger
than the Eddington rate. Feedback from supernovae and from the MBHs themselves
modulates the growth of the first MBHs. While current observational data only
probe the most massive and luminous MBHs, the tip of the iceberg, we will soon
be able to test theoretical models of MBH evolution on more "normal" MBHs: the
MBHs that are indeed relevant in building the population that we observe in
local galaxies, including our own Milky Way.
