  In this review I demonstrate that a realistic model for the formation of
galaxy disks depends on a proper treatment of the gas in galaxies.
Historically, cosmological simulations of disk galaxy formation have suffered
from a lack of resolution and a physically motivated feedback prescription.
Recent computational progress has allowed for unprecedented resolution, which
in turn allows for a more realistic treatment of feedback. These advances have
led to a new examination of gas accretion, evolution, and loss in the formation
of galaxy disks. Here I highlight the role that gas inflows, the regulation of
gas by feedback, and gas outflows play in achieving simulated disk galaxies
that better match observational results as a function of redshift.
