Advanced information regarding the topic of x-ray spectroscopy has been described in this book. X-ray is the only invention that became a routine diagnostic tool in hospitals within a week of its first observation by Roentgen in 1895. Till date, x-ray technology serves as an excellent characterization tool for scientists engaged in nearly all fields, including physics, space science, medicine, archeology, medicine, chemistry, metallurgy, and material science. With an already extensive range of existing applications of x-rays, it comes as a surprise that every day people are discovering novel applications of x-rays or developing the existing methods. The book has been compiled with selective information regarding the current applications of x-ray spectroscopy which are of significant interest to the engineers and scientists engaged in the fields of astrophysics, material science, astrochemistry, chemistry, instrumentation, physics, and methods of x-ray based characterization. The book elucidates fundamental principles of satellite x-rays as characterization devices for the physics of detectors, chemical properties and x-ray spectrometer. It also elucidates techniques like EPMA, EDXRF, satellites, WDXRF, particle induced XRF, matrix effects, and micro-beam analysis. The characterization of ceramic materials and thin films with the help of x-rays has also been described.