Piezoelectric materials generate an electric charge when they are mechanically stressed. This property allows them to convert mechanical energy into electrical energy and vice versa. Common examples of piezoelectric materials include certain crystals, ceramics, and even some biological materials. These materials are widely used in various applications, such as in microphones, speakers, and sensors. When pressure is applied to a piezoelectric material, it produces a voltage, which can be harnessed for electronic devices. Conversely, applying an electric field can cause these materials to change shape, making them useful in actuators and precision movement systems.