  The connection between cosmological observations and neutrino physics is
discussed in detail. Neutrinos decouple from thermal contact in the early
Universe at a temperature of order 1 MeV which coincides with the temperature
where light element synthesis occurs. Observation of light element abundances
therefore provides important information on such properties as neutrino energy
density and chemical potential. Precision observations of the cosmic microwave
background and large scale structure of galaxies can be used to probe neutrino
masses with greater precision than current laboratory experiments. In this
review I discuss current cosmological bounds on neutrino properties, as well as
possible bounds from upcoming measurements.
