  Comparative analysis of three stabilization mechanisms of unstable states of
physical systems is presented in this review. These mechanisms are: the quantum
Zeno effect, the stabilization of unstable states in an external fast
oscillating field (i.e. the Kapitza pendulum), and the mechanism named as the
spinning top mechanism. The common features of these mechanisms, as well as the
differences between them, are analyzed in the paper. In particular, it is shown
that the stabilization of quantum systems is possible without involvement of
such concept as the collapse of wave function. For stabilization it is
sufficient to have a stabilizing radiation flow with the Rabi frequency of
transitions exceeding some frequency. This frequency is inversely proportional
to the lifetime of the state under stabilization. It is shown that the Top
principle allows stabilizing unstable systems using affecting only those states
to which these systems must go over.
  It is shown that stabilization of unstable states by impact of rapidly
oscillating forces occurs by non-self-consistent exposure, i.e. the dynamics of
stabilizing field is independent on the dynamics of the stabilized state.
Stabilization using the spinning top principle involves self-consistent forces,
and thus, in many cases can be the most effective mechanism of stabilization.
