  Far-infrared and submillimeter wavelength surveys have now established the
important role of dusty, star-forming galaxies (DSFGs) in the assembly of
stellar mass and the evolution of massive galaxies in the Universe. The
brightest of these galaxies have infrared luminosities in excess of 10$^{13}$
L$_{\odot}$ with implied star-formation rates of thousands of solar masses per
year. They represent the most intense starbursts in the Universe, yet many are
completely optically obscured. Their easy detection at submm wavelengths is due
to dust heated by ultraviolet radiation of newly forming stars. When summed up,
all of the dusty, star-forming galaxies in the Universe produce an infrared
radiation field that has an equal energy density as the direct starlight
emission from all galaxies visible at ultraviolet and optical wavelengths. The
bulk of this infrared extragalactic background light emanates from galaxies as
diverse as gas-rich disks to mergers of intense starbursting galaxies. Major
advances in far-infrared instrumentation in recent years, both space-based and
ground-based, has led to the detection of nearly a million DSFGs, yet our
understanding of the underlying astrophysics that govern the start and end of
the dusty starburst phase is still in nascent stage. This review is aimed at
summarizing the current status of DSFG studies, focusing especially on the
detailed characterization of the best-understood subset (submillimeter
galaxies, who were summarized in the last review of this field over a decade
ago, Blain et al., 2002), but also the selection and characterization of more
recently discovered DSFG populations. We review DSFG population statistics,
their physical properties including dust, gas and stellar contents, their
environments, and current theoretical models related to the formation and
evolution of these galaxies.
