  In this review, we emphasize the interplay between astrophysical
observations, modeling, and nuclear physics laboratory experiments. Several
important nuclear cross sections for astrophysics have long been identified
e.g. 12C(alpha,gamma)16O for stellar evolution, or 13C(alpha,n)16O and
22Ne(alpha,n)25Mg as neutron sources for the s-process. More recently,
observations of lithium abundances in the oldest stars, or of nuclear gamma-ray
lines from space, have required new laboratory experiments. New evaluation of
thermonuclear reaction rates now includes the associated rate uncertainties
that are used in astrophysical models to i) estimate final uncertainties on
nucleosynthesis yields and ii) identify those reactions that require further
experimental investigation. Sometimes direct cross section measurements are
possible, but more generally the use of indirect methods is compulsory in view
of the very low cross sections. Non-thermal processes are often overlooked but
are also important for nuclear astrophysics, e.g. in gamma-ray emission from
solar flares or in the interaction of cosmic rays with matter, and also
motivate laboratory experiments. Finally, we show that beyond the historical
motivations of nuclear astrophysics, understanding i) the energy sources that
drive stellar evolution and ii) the origin of the elements can also be used to
give new insights into physics beyond the standard model.
