We discuss the basic principles of the process of x-ray absorption in condensed systems. It is shown how x-ray absorption spectroscopy (XAS) can be used to determine both local atomic structure and local electronic structure in materials. We discuss the use of x-ray absorption fine structure (XAFS) in crystalline materials in which the interaction between electrons and ions produces changes in the local atomic structure as a result of electronic changes. As a specific example we discuss the case of photoinduced structural changes in doped II-VI semiconductors. We also illustrate the use of X-ray Absorption Near Edge Structure (XANES) to discern local brake of crystal symmetry in materials, which exhibit correlated motions of ions and electrons, taking as an example the oxide PrNiO3.