In this review article, we have analysed the overview of the dielectric parameters of liquid crystals (LCs) such as nematic, smectic with the function of frequency and temperature.LCs are isotropic with anisotropic dielectric nature. When the dielectric anisotropy was affected by the cause director reorientation in an applied electric field, deepening our understanding of dielectric response has been a leading theme in the development of LC science. Herein, we have studied the dielectric permittivity, dielectric loss and relaxation behaviour of nematic and smectic LCs. The molecular theory of LC has been explained by Maier and Saupe and then used it to explain how nematic order influences dielectric relaxation in LCs.