In recent years, synchrotron radiation (SR) and free-electron lasers (FELs) have been playing an important role for the radiation sources in the region of the ultraviolet (UV) and X-ray wavelengths. From the viewpoint of classical electrodynamics, this article briefly reviews the basic principles of synchrotron radiation and free-electron lasers. In particular, special attention is paid to research efforts in the UV and X-ray free-electron lasers.
