Once a UV–visible spectrum acquired, the question of the signal exploitation arises. From a qualitative point of view, several handling methods are available for spectra interpretation such as spectra shape comparison, derivative spectra, or research of isosbestic points from a set of spectra. For the determination of concentrations of dissolved compounds or the estimation of aggregate parameters or indices, the simplest way is to use a colorimetric approach with the study of the relation with the absorbance value at one wavelength. However, this approach is limited and several other methods can be used for more robust results among the exploitation of absorbance values at two wavelengths, second derivative calculation, principal component analysis, partial least squares regression, or spectral deconvolution. An overview of methods applied is given at the end of this chapter