This book concentrates on the luminescence and structural properties of the new generation of europium and terbium activated phosphors, associated phenomena, and related topics, from basic principles to the most recent discoveries. It summarizes the present state of the art in this rapidly growing field. The authors describe recent developments in the areas of rare earth doped phosphors and of some new materials or well-known materials with improved properties that open up new possibilities. The areas of focus include X-ray phosphors, phosphors for light-emitting devices, emissive displays, and fluorescent lamps. The book comprises theoretical and experimental analysis of various properties of phosphors, research methods and preparation techniques, and some promising applications.