Recent developments in X-ray spectroscopy in the last decade are reviewed. A specific emphasis is placed on displaying the strong natural connection between X-ray spectroscopy and materials science. Brief explanations of several X-ray spectroscopic methods are given. X-ray spectroscopic instruments such as table-top X-ray sources are discussed in detail, whereas those employing synchrotron and other sources are briefly addressed. The spectroscopic methods and results from materials investigations are reviewed according to their positions in a 3D parameter space of time, length, and energy. New experimental measurements on atoms, molecules, nanomaterials, and bulk materials that include insulators, semiconductors, metals and magnetic materials using both static and time-resolved methods are reviewed.