Neutrinos have flavors which can mix because their mass basis is different from their flavor basis. This can lead to neutrino oscillations in vacuum that are modified by an effective potential induced by forward-scattering in a medium. At high neutrino densities, neutrino self-interactions further modify oscillations and non-forward scattering also becomes relevant.
The description of flavor conversions and scattering can be unified in a framework of so-called non-abelian Boltzmann equations for
quantum kinetics which consist of a classical Vlasov-type and a quantum part. This can lead to a plethora of interesting effects including
collective neutrino oscillations and instabilities that are mathematically similar to plasma instabilities. We give an overview of these effects and of neutrino quantum kinetics in general.