  To study large-scale structure in the Universe a full census of the contents
are required. This is even more important when the processes of galaxy
formation are being investigated. In the last year the population of distant
galaxies that emit most of their energy in the infrared waveband have been
studied in unprecedented detail. The intensity of background radiation at
wavelengths between 3 mm and 10 microns has been determined to within a factor
of about 2, and much of this background radiation has been resolved into
individual galaxies. These galaxies are largely hidden from view in the optical
waveband by absorption due to interstellar dust. By combining this new
knowledge with the ever growing body of information gathered using optical
telescopes, the process of galaxy formation is slowly being revealed. Great
opportunities for studying the distant Universe are promised by advances in
instrumentation in the millimeter (mm), submm and far-infrared wavebands over
the next decade.
