Polar liquid crystals - ferro, antiferro, banana, and columnar -

Brief overview of polar liquid crystals (LCs) is given with a tutorial manner. They are chiral smectic C ferroelectric LCs (FLCs), chiral smectic C-A antiferroelectric LCs (AFLCs), their ferrielectric subphase LCs, chiral columnar FLCs, chiral and nonchiral ferronematic LCs, various bent-shaped polar LCs such as B1, B2, B4, B7, twist-bend nematic, orthogonal polar smectic, and nonchiral columnar FLCs. After summarizing the definition of FLCs and AFLCs, and techniques to certify these polar LCs, their polar structures and characteristics are described together with important review articles.