Spectroscopy of nuclei, atoms, ions and molecules belongs today to the group of the most important and most common methods of instrumental analytics. High-tech emission, absorption and fluorescence spectrometers provide accurate determination of the qualitative and quantitative composition of gaseous, liquid and solid substances, allow studying surface layers of materials, conducting local and layer-by-layer analysis. This monograph provides an overview of various modern methods of nuclear, atomic, ion and molecular spectrometry, as well as instruments implementing these methods. Many analytical problems solved in laboratories of industrial enterprises, in natural science and technical institutions, as well as issues of study and protection of environmental objects are considered.