Abstract We briefly review the basic theory and recent applications in the X-ray absorption fine structure (XAFS) spectroscopy. First we discuss a dressed one-electron XAFS formula starting from many-body scattering theory, where important many-body effects, intrinsic and extrinsic losses, and optical potential are naturally introduced. Next multiple scattering renormalization, and spherical wave effects are discussed. Phonon effects such as Debye–Waller factors are also discussed. Some interesting XAFS applications, in particular, ultrafast XAFS and XAFS applications to nano-particles are discussed in some detail.