The experimental techniques of infrared and Raman spectroscopy of solid compounds, which are in use at present, are recalled and the assignment of the observed spectra and their interpretation with respect to structure and bonding of the respective compound are discussed. The main topics are distortion of molecular units, disorder, group theory, symmetry coordinates, single-crystal methods, crystal-matrix studies, band broadening and splitting, vibrational coupling phenomena, isotopic effects, characteristic frequencies, effective dynamical charges, lattice dynamical calculations, bond strength, etc.