Infrared spectroscopy involves the interaction of infrared radiation with matter. It covers a range of techniques, mostly based on absorption spectroscopy. As with all spectroscopic techniques, it can be used to identify and study chemical substances. Samples may be solid, liquid, or gas. The method or technique of infrared spectroscopy is conducted with an instrument called an infrared spectrometer (or spectrophotometer) to produce an infrared spectrum. In dairy industry, IR is useful tool for analysis of milk and milk products. It is mainly used for compositional analysis, adulteration detection, quality monitoring of the milk as well as for milk products.