In the last few decades, X-ray Absorption Spectroscopy (XAS) has recorded a remarkable amount of interest in the study of glass structure for its sensitivity to the short range order around a selected atomic species. XAS greatest evolution began in the last century, thanks to an adequate and structurally useful theoretical interpretation of the Extended X-Ray Absorption Fine Structure (EXAFS) beyond the absorption edge and to the contemporaneous advent of synchrotron radiation facilities. The use of EXAFS in the case of nanocrystalline glass-ceramic systems is very important, since the information obtained are complemental to those determined by the Bragg diffraction. This paper gives a brief description of EXAFS theory and analyses methods in the case of disordered systems.
