Neutrinos on Earth and in the Heavens

After a brief introduction to neutrinos, I will discuss the idea of neutrino oscillations. A simple non-technical introduction to oscillations of neutrinos in vacuum as well as in matter (the celebrated MSW effect) will be given. I will then review the unambiguous evidence for neutrino oscillations obtained in solar, atmospheric, reactor and accelerator neutrino experiments. Finally, I will briefly discuss the parametric resonance enhancement of neutrino oscillations in the Earth and prospects of its observation.