  Nuclear astrophysics is that branch of astrophysics which helps understanding
some of the many facets of the Universe through the knowledge of the microcosm
of the atomic nucleus. In the last decades much advance has been made in
nuclear astrophysics thanks to the sometimes spectacular progress in the
modelling of the structure and evolution of the stars, in the quality and
diversity of the astronomical observations, as well as in the experimental and
theoretical understanding of the atomic nucleus and of its spontaneous or
induced transformations. Developments in other sub-fields of physics and
chemistry have also contributed to that advance. Many long-standing problems
remain to be solved, however, and the theoretical understanding of a large
variety of observational facts needs to be put on safer grounds. In addition,
new questions are continuously emerging, and new facts endanger old ideas. This
review shows that astrophysics has been, and still is, highly demanding to
nuclear physics in both its experimental and theoretical components. On top of
the fact that large varieties of nuclei have to be dealt with, these nuclei are
immersed in highly unusual environments which may have a significant impact on
their static properties, the diversity of their transmutation modes, and on the
probabilities of these modes. In order to have a chance of solving some of the
problems nuclear astrophysics is facing, the astrophysicists and nuclear
physicists are obviously bound to put their competence in common, and have
sometimes to benefit from the help of other fields of physics, like particle
physics, plasma physics or solid-state physics.
