Piezoelectricity is the ability of certain crystalline materials to develop an electric charge proportional to a mechanical stress. Since its discovery the piezoelectricity effect has found many useful applications, such as the production and detection of sound, generation of high voltages and frequency, microbalances, and ultra fine focusing of optical assemblies. This book reviews the state of art in polycrystalline piezoelectric ceramic materials, which covers the processing, properties, characterisation, and applications of piezoelectric ceramic materials.