The review deals with the problem of selective interaction of laser radiation with atoms and molecules. Objects of selective interaction (chemical elements and compounds, isotopes, molecular bonds, etc.) are considered first. Next, possible elementary selective processes (photoionization of atoms and molecules, photodissociation and photoisomerization of molecules, photodeflection of particles, photochemical reactivity, etc.) are discussed and the available techniques are classified into photophysical and photochemical methods, atomic and molecular methods, and so on. The review is concerned mainly with the photophysical and photochemical methods of selective interaction in the specific case of laser isotope separation. The last sections of the review deal with other applications which are in the course of development, such as preparation of pure substances, selective laser biochemistry, selective detection of nuclei, atoms, and molecules, and spatial localization of molecular bonds.