Ferroelectric materials are nonlinear dielectrics that can exhibit a spontaneous polarization in the absence of an external electric field. Reorientation of the domain‐state polarization by an external field is the defining characteristic. An important class of ferroelectrics is that of the perovskites. Modified barium titanate and lead zirconate‐lead titanate solid solution‐based ceramics are the most extensively used materials for multilayer capacitors and piezoelectric devices, respectively. Relaxor ferroelectrics arising from the lead‐magnesium niobates are gaining in usage, and ferroelectric thin films are under development. Ferroelectrics are utilized in various polymer‐matrix composite materials in the automotive, imaging, and telecommunications industries.