  The point-contact spectroscopy, in contrast to the tunneling spectrocopy,
considers small electrical contacts with direct conductivity. In the normal
state, it enables one to measure the spectral function of electron-boson
interaction. In the superconducting state, new features appear connected with
the energy dependence of excess current. The non-linearities of the
current-voltage characteristic are due to: i) The inelastic scattering of
electron quasiparticles in the contact region; ii) The energy dependence of the
superconducting energy gap, and iii) The non-equilibrium superconducting
effects. These effects are discussed from the experimental point of view
