Piezoelectrics are crystalline dielectrics that have no centre of symmetry. Crystals with a centre of symmetry are incapable of piezoelectric effect. The presence of other symmetry elements (axis, planes of symmetry) can prohibit the appearance of polarisation in some directions or at deformation, thus limiting the number of piezoelectric crystals.

Piezoelectric properties can be created artificially in some polycrystalline dielectrics by forming so-called piezoelectric textures, for instance, by means of polarisation in the electric field. This is the method used to manufacture piezoceramics, polycrystalline solid solutions subjected to pre-polarisation in an electrical field.

Piezoelectrics are widely used in acoustics, ultrasound technology, broadcasting, acoustic electronics, defectoscopy and other areas.

The first piezoelectric material to be studied in detail (by brothers Jean and Pierre Curie) was crystal quartz, which remains by large a piezoelectric of choice in high-frequency piezoelectric applications because of the low energy losses. In the industry, low-frequency (below 10 MHz) electromechanical transducers are commonly manufactured using piezoelectric ceramics such as barium titanate, lead zirconate titanate, etc. The voltage-length conversion factor in a ceramic specimen with a length of 1 cm is in the order of 1 nm/V. Piezoelectric ceramics are widely used in the manufacture of one key component of scanning tunnelling and atomic force microscopes (STM and AFM), the cantilever, which is attached to the tip of the microscope and used to examine the surface with atomic step size (about 0.1 angstroms).