The pupose of this paper is to provide both an introductory and advenced picture of dielectric relaxation in solids and dielectric data intrepertation as a result of the continuosly incresing application of Dielectric Spectroscopy(DS) in research projects. This involves a description of the principle of DS that are useful for any practical situation irrespective of the field where its application being considered. treatment of this aspects is given on very simple physical grounds empasizing the meaning of the concepts rather than mathematical background of DS.