**Abstract**

Spectrophotometry and different types of spectroscopy are the technique that involved in identifying and quantifying the amount of a known substance in an unknown medium. Spectroscopy is the most convenient method for analysis of unknown samples both qualitatively and quantitatively with a good percentage of accuracy. Different types of spectroscopic and spectrophotometric techniques are very helpful in analyzing the samples even at sub-ppm level particularly in the field of scientific research. These techniques based on the simple principle that the amount of specific radiation i.e. ray or light (photon) absorbed or reflected by the sample relative to the intensity of the incident ray/light at a particular wavelength. These techniques are using, for analyzing purity, % content in mixture, type of reactions/chemical interactions occur/absorption or reflectance of color for a colored substances/solutions are detectable and quantitatively determinable quantitative determination. Most of the scientists have been using different spectroscopic and spectrophotometric techniques like Infrared spectroscopy, Raman spectroscopy, X-ray fluorescence and UV VIS spectrophotometry etc., which are playing an important role in the identification and characterization of substances, apart from this the atomic absorption spectroscopy and atomic emission spectroscopy are also being used for quantitative measurement of different substances or elements.

**Keywords:** spectroscopy, spectrophotometry, UV-visible spectroscopy, infrared spectroscopy, Raman spectroscopy, X-ray fluorescence
