This book presents a detailed description of the most common nondestructive testingNDT techniques used for the testing and evaluation fiberreinforced composite structures during manufacturing andor in service stages. In order to facilitate the understanding and the utility of the different NDT techniques presented the book first provides some information regarding the defects and material degradation mechanisms observed in fiberreinforced composite structures as well as their general description and most probable causes. It is written based on the extensive scientific research and engineering backgrounds of the authors in the NDT and structural health monitoring SHM of structural systems from various areas including electrical mechanical materials civil and biomedical engineering.