Piezoelectric are materials that can create electricity when subjected to a mechanical stress. They will also work in reverse, generating a strain by the application of an electric field. The piezoelectric effect describes the relation between a mechanical stress and an electrical voltage in solids. In physics, the piezoelectric effect can be described as the link between electrostatics and mechanics. The piezoelectric effect was discovered in 1880 by the Jacques and Pierre Curie brothers. One of the first applications of the piezoelectric effect was an ultrasonic submarine detector developed during the First World War. The piezoelectric effect occurs only in non-conductive materials. This book emphasises on the various applications of piezoelectric materials such as piezoelectric stacks in level sensors, pressure sensors, machining processes, nondestructive testing of aeronautical structures and acoustic wave velocity measurements etc. The book should be of immense valuable tool not only to researchers, but also to professional engineers, students and other experts in a variety of disciplines, both academic and industrial seeking to gain a better understanding of what has been completed in the field recently, and what kind of open problems are in this area.