  The James Clerk Maxwell Telescope (JCMT) has been the world's most successful
single dish telescope at submillimetre wavelengths since it began operations in
1987. From the pioneering days of single-element photometers and mixers,
through the first modest imaging arrays, leading to the state-of-the-art
widefield camera SCUBA-2 and the spectrometer array HARP, the JCMT has been
associated with a number of major scientific discoveries. Famous for the
discovery of "SCUBA" galaxies, which are responsible for a large fraction of
the far-infrared background, to the first images of huge discs of cool debris
around nearby stars, possibly giving us clues to the evolution of planetary
systems, the JCMT has pushed the sensitivity limits more than any other
facility in this most difficult of wavebands in which to observe. Now
approaching the 30th anniversary of the first observations the telescope
continues to carry out unique and innovative science. In this review article we
look back on just some of the scientific highlights from the past 30 years.
