  A consensus is developing on the nature of various populations of absorbers
at different redshift regimes and in particular on their relationships to
galaxies at those epochs. As one example we discuss the population of z < 1
MgII absorbers. Kinematic models are presented that show this population to be
consistent with some combination of halo and disk kinematics and not with a
pure disk or halo model. In contrast, the 2 < z < 3 CIV absorbers are likely to
represent a mix of already formed halos and protogalactic clumps in the process
of assembly. Clues could be provided by the level at which SiIV traces the same
kinematic components as CIV (relative to how it traces lower ionization gas)
and this is illustrated by a simple application of principal components
analysis. It remains uncertain how much unambiguous information it will be
possible to extract about the detailed properties of the gas along the line of
sight through an individual absorption profile. However, ratios of various low
and high ionization transitions along the line of sight can be combined with
insights gained from kinematic models and from observations of galaxy
properties. There is reason for optimism that we will progress toward a point
when we will someday study the interstellar medium and gaseous halos and
environments of absorbing galaxies at close to the same level as we study these
components in the Milky Way.
