Improving and extending performance at synchrotron radiation facilities

Synchrotron radiation facilities around the world have now matured through three generations. The latest facilities have all met or exceeded their design specifications and are learning how to cope with the ever more demanding requests of the user community, especially concerning beam stability. The older facilities remain competitive by extending the unique features of their design, and by developing novel insertion devices. In this paper we survey the beam characteristics achieved at third-generation sources and explore the improvements made at earlier generation facilities