Publisher Summary Crystal optics is based on the discovery of x-ray diffraction in crystals in the well-known experiment of Max von Laue and his colleagues. The development of imaging crystal optics then ceased because electron microscopy could provide better resolution. However, that technique has some disadvantages for imaging biological materials because specimens have to be thinned and heavy-metal stains are needed to enhance the low natural contrast. Classical x-ray spectroscopy, because of its long history, has been reviewed many times and commercial instruments have been developed. The application of classical x-ray spectroscopy techniques to new ultrabrilliant sources still faces some challenges, but it will lead to a new understanding of physical phenomena becuase, for example, ultrashort phenomena can be studied in real time.