  Point-contact spectroscopy was originally developed for the determination of
the electron-phonon spectral function in normal metals. However, in the past 20
years it has become an important tool in the investigation of superconductors.
As a matter of fact, point contacts between a normal metal and a superconductor
can provide information on the amplitude and symmetry of the energy gap that,
in the superconducting state, opens up at the Fermi level. In this paper we
review the experimental and theoretical aspects of point-contact spectroscopy
in superconductors, and we give an experimental survey of the most recent
applications of this technique to anisotropic and multiband superconductors.
