The fingerprint region in IR spectroscopy is the range from approximately 1500 to 600 cm\(^{-1}\). This region contains complex, overlapping absorption bands arising from C–O, C–N, C–X stretching and various bending vibrations that are unique to each molecule — like a molecular fingerprint. The region 4000–2500 cm\(^{-1}\) is the functional group region (X–H stretches).