Photoinitiating systems play a key role in the starting point of a polymerization reaction under exposure to a UV or a visible light. The number of publications discussing photoinitiating systems for polymerization has seen a significant growth in recent years and this book provides an update on their latest research developments. The book covers different types of photoinitiating systems including UV radical photoinitiators, long wavelength sensitive radical photoinitiators, cationic photoinitiators and water soluble photoinitiators as well as a chapter on how to design novel photoinitiators. The book then focusses on the applications of the photoinitiators from nanoparticles and materials to ionic liquids and solar cells. Edited by leading names in the field, the book is suitable for postgraduate students and researchers in academia and industry interested in polymer chemistry, organic chemistry, materials science and the applications of the materials.