The current state of the problem of the local field of a light wave in liquid crystals is analyzed in the theoretical and experimental aspects. The fundamental properties of the local-field tensor are studied within the framework of various theoretical approaches. A connection is established between the anisotropy of the local field and the molecular and macroscopic parameters of liquid crystals, their orientational and translational order, and the character of the intermolecular correlations. The effects of the local field in refractometry, absorption spectroscopy, and Raman scattering in liquid crystals are discussed. The strong influence of the anisotropy of the local field on the moments of the orientational distribution function (the order parameter), as determined from molecular-optics experiments, the molecular susceptibility tensors, and the spectrum of intrinsic and impurity absorption and other characteristics of liquid crystals are studied. Experimental methods of determining the parameters of the local field in liquid crystals are examined.