This book provides a comprehensive overview of Acoustic Emission Testing (AET), a non-destructive testing (NDT) technique used to monitor changes in material behavior over time without altering the components being tested. AET is unique in its ability to detect crack propagation both on the surface and deep inside materials, making it valuable for structural health monitoring. The book covers the historical background, fundamental principles, and practical applications of AET, including its use in concrete, rock, wood, superstructures, and substructures. It also discusses the challenges and limitations of AET, such as signal reproducibility and the need for advanced data processing techniques. The editors, Christian U. Grosse and Masayasu Ohtsu, highlight the importance of AET in various engineering contexts and emphasize the need for reliable sensor technology and data interpretation methods. The book is intended for engineers and researchers interested in non-destructive testing and material evaluation.This book provides a comprehensive overview of Acoustic Emission Testing (AET), a non-destructive testing (NDT) technique used to monitor changes in material behavior over time without altering the components being tested. AET is unique in its ability to detect crack propagation both on the surface and deep inside materials, making it valuable for structural health monitoring. The book covers the historical background, fundamental principles, and practical applications of AET, including its use in concrete, rock, wood, superstructures, and substructures. It also discusses the challenges and limitations of AET, such as signal reproducibility and the need for advanced data processing techniques. The editors, Christian U. Grosse and Masayasu Ohtsu, highlight the importance of AET in various engineering contexts and emphasize the need for reliable sensor technology and data interpretation methods. The book is intended for engineers and researchers interested in non-destructive testing and material evaluation.