On the nature of sub-millimetre galaxies

I discuss our current understanding of the nature of high-redshift (z > 2) (sub)-millimetre-selected galaxies, with a particular focus on whether their properties are representative of, or dramatically different from those displayed by the general star-forming galaxy population at these epochs. As a specific case study, I present some new results on the one sub-millimetre galaxy which happens to lie within the Hubble Ultra Deep Field and thus benefits from the very best available ultra-deep optical-infrared Hubble Space Telescope and Spitzer Space Telescope imaging. I then consider what these and other recent results from optical-infrared studies of sub-millimetre and millimetre selected galaxies imply about their typical masses, sizes and specific star-formation rates, and how these compare with those of other star-forming galaxies selected at similar redshifts. I conclude with a brief discussion of the continued importance and promise of SCUBA2 in the era of Herschel.