Synchrotron radiation as a spectroscopic research tool has undergone a most inter esting and astonishing historical development and has now come to the stage of an exciting boom. The machines which produce synchrotron radiation were built and de veloped exclusively for other purposes in the past, namely high-energy physics. At the same time, however, they involuntarily became better and better light sources for the spectral range from the visible to the hard x-ray region. Now we are at the point that the first few storage rings have gone into operation as machines dedicated to synchrotron...