What are sterile neutrinos good for?

Taken at face value, current experimental data indicate the existence of anew particle, the sterile neutrino, which must be a singlet under the StandardModel gauge group. Although they are not detectable through traditional means,such particles have interesting observable consequences for particleastrophysics and cosmology. Here we examine these implications and discuss, inparticular, sterile neutrino dark matter and the relationship betweenmatter-enhanced active-sterile neutrino transformation and the synthesis ofheavy elements in supernovae