Abstract : We discuss the recent progress in our understanding of neutrino flavour conversion in core-collapse supernovae and focus on the effects coming from the neutrino-neutrino interaction. The latter has been shown to engender new phenomena, modifying significantly the neutrino fluxes and supernova observations. In particular, we make the link between the spectral split and the magnetic resonance phenomenon. Moreover, recent investigations have demonstrated the existence of leptonic CP violation effects on the supernova neutrino fluxes. We summarize these findings.