This book describes the basic properties of charged beam transport and the theory of accelerators with radiative damping. The characteristics of the third generation synchrotron radiation sources are analyzed and compared to those of the first and second generations. This is followed by the conceptual and technological problems associated with the discovery of the fourth generation sources. Within this framework, the role played by free electron laser devices is discussed and relevant theoretical and technological aspects of storage-ring and Linac-based sources are analyzed.