Submillimetre astronomy, (at wavelengths of 200µm to 1mm), is most sensitive to very cold gas and dust. For example, a source with a temperature of 10 K (-263 C) emits most of its energy in a broad spectral region centred around 300 microns. Such very cold material is associated with objects in formation, that is, the mysterious earliest evolutionary stages of galaxies, stars and planets. If one wants to understand the origins of these most fundamental of astronomical structures, the submillimetre is the waveband of choice.