High-redshift star formation in the ALMA era
  The Atacama Large Millimetre/submillimetre Array (ALMA) is currently in the
process of transforming our view of star-forming galaxies in the distant
($z\gtrsim1$) universe. Before ALMA, most of what we knew about dust-obscured
star formation in distant galaxies was limited to the brightest submillimetre
sources$-$the so-called submillimetre galaxies (SMGs)$-$and even the
information on those sources was sparse, with resolved (i.e., sub-galactic)
observations of the obscured star formation and gas reservoirs typically
restricted to the most extreme and/or strongly lensed sources. Starting with
the beginning of early science operations in 2011, the last nine years of ALMA
observations have ushered in a new era for studies of high-redshift star
formation. With its long baselines, ALMA has allowed observations of distant
dust-obscured star formation with angular resolutions comparable to$-$or even
far surpassing$-$the best current optical telescopes. With its bandwidth and
frequency coverage, it has provided an unprecedented look at the associated
molecular and atomic gas in these distant galaxies through targeted follow-up
and serendipitous detections/blind line scans. Finally, with its leap in
sensitivity compared to previous (sub-)millimetre arrays, it has enabled the
detection of these powerful dust/gas tracers much further down the luminosity
function through both statistical studies of color/mass-selected galaxy
populations and dedicated deep fields. We review the main advances ALMA has
helped bring about in our understanding of the dust and gas properties of
high-redshift ($z\gtrsim1$) star-forming galaxies during these first nine years
of its science operations, and we highlight the interesting questions that may
be answered by ALMA in the years to come.
