"Characterization I" is a specialized book that delves deeply into the characterization of molecular sieves. It is part of a comprehensive book series that addresses the science and technology of zeolites as well as related microporous and mesoporous materials. The contributions come from recognized experts in their field and are thematically organized, with each volume covering a specific subfield. In this first volume on characterization, the key spectroscopic techniques are presented, including IR, Raman, NMR, EPR, UV-VIS spectroscopy, as well as X-ray absorption, photoelectron, and Mössbauer spectroscopy. The book offers a balanced mix of theoretical foundations, experimental approaches, and practical applications illustrated by selected examples.