The document discusses piezoelectricity and various applications of piezoelectric materials and devices. It covers piezoelectric sensors, actuators, motors, and transformers. Piezoelectric sensors convert mechanical energy into electrical signals and are used where high temperatures, pressures, or dynamic measurements are required. Piezoelectric actuators and motors convert electrical signals into precise mechanical motion or displacement using the inverse piezoelectric effect. Piezoelectric transformers perform electromechanical energy conversion without magnetic fields to efficiently transfer power for electronics. Applications include optics, medical devices, flow control and more.