NMR spectroscopy is a technique that uses radio waves to analyze atomic nuclei and determine molecular structure. It can be used to study nuclei such as 1H, 13C, and 19F. The instrument applies a magnetic field to sample nuclei, and measures electromagnetic radiation absorbed or emitted during transitions between nuclear spin energy levels. Chemical shifts are observed as differences in resonant frequencies due to shielding by nearby electrons. NMR provides information about molecular structure through analysis of chemical shifts, spin multiplicity, coupling constants, and integration of peak areas. It has applications in medicine, biochemistry, organic chemistry, and other fields.