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Abstract A general introduction is given to the principles and theory of Raman spectroscopy, the discipline dealing with spectral analysis of inelastic scattering of light by the vibrating molecules in liquids, solids, or gases – the phenomenon called Raman scattering. The origin of Raman scattering and its association with molecular polarizability is outlined in this article. The frequency relations of the vibrational Raman effect are developed in terms of the classical theory of electromagnetic radiation. A simplified description of the factors governing the directional properties, intensity relations, and polarization characteristics of the scattered radiation are given by the classical theory, which are then refined according to a partial quantum mechanical treatment. The vibrational selection rules including the role of molecular symmetry are demonstrated using select examples of diatomic and polyatomic molecules, contrasting infrared and Raman spectroscopy and emphasizing their complementary nature.