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Abstract
Brief history of ferroelectric and antiferroelectric liquid crystals is described. To reduce the symmetry of the molecular systems, two ideas were successfully used; introductions of chirality and molecular shape asymmetry. The chirality introduced into rod-shaped and disc-shaped molecular systems led to chiral smectic C and chiral discotic columnar phases. Dogleg from rod and cone or bowl from disc in molecular shapes brought about polar organization by their packing, realizing so-called banana phases and polar columnar phases, respectively. Particularly, bent-core mesogens exhibit a variety of novel polar phases. In addition to such established polar structures, some evidences about polar structures realized in polar nematic and cholesteric phases are given in some detail. Attempts for the application of these polar liquid crystals such as displays are also overviewed.