  Using a system of the corresponding Schwinger-Dyson equations of motion, a
pure dynamical theory of quark confinement and spontaneous breakdown of chiral
symmetry is formulated. It is based on dominated in the QCD vacuum
self-interaction of massless gluons only, i.e., without involving some extra
degrees of freedom. This interaction becomes strongly singular in the deep
infrared domain leading thus to the enhancement of zero momentum modes in the
nonperturbative QCD vacuum. Using theory of distributions, complemented by the
dimensional regularization method, we have explicitly shown that strong
infrared singularities can be put under control. In this way a new phase in
QCD, intrinsically nonperturbative QCD which is manifestly gauge invariant, was
discovered. As a result, a highly nontrivial dynamical and topological
structure of the QCD vacuum has emerged within our approach. We have also
explicitly shown how infrared multiplicative renormalization program should be
done in order to self-consistently remove all the strong infrared singularities
from the theory. The corresponding convergence conditions play a crucial role
in this program. In this theory any physical observables are determined by such
correlation functions from which all types of the perturbative contributions
should be subtracted, by definition. Theory is not only infrared finite but it
is free from the ultraviolet divergences as well. It has a mass gap $\Delta >
0$, i.e., there are no physical states in the interval $(0, \Delta)$. It
explains confinement, spontaneous breakdown of chiral symmetry and other
nonperturbative effects on a general ground and in self-consistent way.
