Galaxy Formation: Where Do We Stand?
  This paper presents a review of the topic of galaxy formation and evolution,
focusing on basic features of galaxies, and how these observables reveal how
galaxies and their stars assemble over cosmic time. I give an overview of the
observed properties of galaxies in the nearby universe and for those at higher
redshifts up to z~10. This includes a discussion of the major processes in
which galaxies assemble and how we can now observe these - including the merger
history of galaxies, the gas accretion and star formation rates. I show that
for the most massive galaxies mergers and accretion are about equally important
in the galaxy formation process between z = 1-3, while this likely differs for
lower mass systems. I also discuss the mass differential evolution for
galaxies, as well as how environment can affect galaxy evolution, although mass
is the primary criteria for driving evolution. I also discuss how we are
beginning to measure the dark matter content of galaxies at different epochs as
measured through kinematics and clustering. Finally, I review how observables
of galaxies, and the observed galaxy formation process, compares with
predictions from simulations of galaxy formation, finding significant
discrepancies in the abundances of massive galaxies and the merger history. I
conclude by examining prospects for the future using JWST, Euclid, SKA, and the
ELTs in addressing outstanding issues.
