Neutrinos in cosmology, with some significant digressions

Neutrinos play prominent roles in both particle physics and cosmology. In this talk, I will cover two broad topics. The first will be possible origins for neutrino masses and mixings and the implications of this physics for cosmology. Some non-cosmological digressions on the flavour problem in general will be made. The second topic will be Big Bang Nucleosynthesis (BBN) and bounds on active-sterile neutrino mixing.