  Elastic scattering of alpha-particle and some tightly-bound light nuclei has
shown the pattern of rainbow scattering at medium energies, which is due to the
refraction of the incident wave by a strongly attractive nucleus-nucleus
potential. This review gives an introduction to the physics of the nuclear
rainbow based essentially on the optical model description of the elastic
scattering. Since the realistic nucleus-nucleus optical potential (OP) is the
key to explore this interesting process, an overview of the main methods used
to determine the nucleus-nucleus OP is presented. The refractive rainbow-like
structures observed in other quasi-elastic scattering reactions have also been
discussed. Some evidences for the refractive effect in the elastic scattering
of unstable nuclei are presented and perspectives for the future studies are
discussed.
