X-ray spectroscopy is a powerful analytical tool for elemental analysis and also for the study of nuclear properties. In recent years there has been extensive utilization of X-ray spectral analysis for the purpose of plasma diagnostics. These studies are vital for the development of controlled nuclear fusion technology. The formation of special atoms containing particles heavier than electrons is another area in which X-ray spectra give detailed knowledge of the sizes and shapes of atomic nuclei, masses and magnetic momenta of bound particles, and the nature of interaction between bound particle and the nucleus. All these aspects make X-ray spectra a uniquely rick source of information on material and nuclear properties. The present article provides some glimpses of how this information is extracted. The choice of topics is biased towards nuclear physics. The presentation is not attempted to be exhaustive and is aimed at conveying the essential physical ideas without going into technical details.