Luminescent materials with advanced performance are in the research hot spot with the recent technical developments of the display, lighting, and fluorescence labeling. Rare-earth-doped luminescent materials have been the focus of the research community owing to their wide applications in display devices, temperature sensors, solar cells, biomedical fields, optoelectronics, etc. This book covers the broad aspects of organic and inorganic materials based phosphors. The purpose of this book is to provide an up-to-date account of the present status and advancement of various techniques of synthesis of luminescent materials and their advanced applications in different areas. This book will cover all the experimental and theoretical approaches related to the rare-earth-doped luminescent materials. It also contains all the necessary information about the rare-earth-doped luminescent materials that were used in the past few years. In a nutshell, this book provides a unique platform to the newcomers who are planning to do research on rare-earthdoped luminescent materials as well as the researchers who are well established in this field.