  The very special characteristic of the proximity effect in
superconductor-ferromagnet systems is the damped oscillatory behavior of the
Cooper pair wave function in a ferromagnet. In some sense, this is analogous to
the inhomogeneous superconductivity, predicted long time ago by Larkin and
Ovchinnikov (1964), and Fulde and Ferrell (1964), and constantly searched since
that. After the qualitative analysis of the peculiarities of the proximity
effect in the presence of the exchange field, the author provides a unified
description of the properties of the superconductor-ferromagnet
heterostructures. Special attention is paid to the striking non-monotonous
dependance of the critical temperature of the multilayers and bilayers on the
ferromagnetic layer thickness and conditions of the realization of the "Pi"-
Josephson junctions. The recent progress in the preparation of the high quality
hybrid systems permitted to observe on experiments many interesting effects,
which are also discussed in the article. Finally, the author analyzes the
phenomenon of the domain-wall superconductivity and the influence of
superconductivity on the magnetic structure in superconductor-ferromagnet
bilayers.
