Frontiers of particle accelerators in the world

Human research on the microcosm is the motive force behind the development of particle accelerators, which have been advancing towards higher luminosity and better performance. Along with deeper progress in research, accelerators have moved step by step from low to high energy, from weak to strong focusing and from fixed target to beam collision. Higher energy and higher luminosity are two frontiers of accelerators for particle physics. As multidiscipline platforms, synchrotron radiation facilities, free electron lasers and spallation neutron sources have been developing rapidly. A variety of low-energy accelerators have been applied throughout a wide range of the economy. New methods, new technologies and new principles have emerged in an endless stream. The international frontiers of particle accelerators are described in this paper.