Nuclear physics plays an essential role in the dynamics of a type II supernova (a collapsing star). Recent advances in nuclear many-body theory allow now improved calculations of the stellar weak-interaction rates involving nuclei. The most important process is the electron capture on finite nuclei with mass numbers A>55. This process is the source of neutrinos during the collapse phase. Neutrino--nucleus reactions occur during the collapse and explosion phase. They play an interesting role for supernova nucleosynthesis. Spectroscopy by supernova neutrino detectors is a fascinating goal for the observation of the next close-by supernova.

PACS numbers: 97.60.Bw, 26.30.+k, 26.50.+x