High-energy diffraction has become a hot and fashionable subject in recent years due to the great interest triggered by the HERA and Tevatron data. These data have helped to show the field from a different perspective paving the road to a hopefully more complete understanding than hitherto achieved. The forthcoming data in the next few years from even higher energies (LHC) promise to sustain this interest for a long time. We believe that it is therefore necessary to summarize the main devel opments which have marked the growth of high-energy diffractive physics in recent decades, and to...