Over the past ten years, the evidence for neutrino mass and mixing has gone from suggestive to compelling to convincing. Based on experimental evidence from atmospheric, solar, reactor, and accelerator neutrinos we now believe that neutrinos are created in weak interaction (flavor) eigenstates, but that these flavor eigenstates are superpositions of physical or `propagation' eigenstates. The experimental and theoretical consequences of these discoveries are great, ranging from neutrino `interferometry' as a probe of new interactions to the possible role of neutrinos in creating our matter-dominated Universse. And unlike the rest of the Standard Model of particle physics which has been mapped in great detail, this new region that has opened up is almost completely unknown. I will review the recent discoveries and their implications, as well as the prospects for the future exploration of this new sector of physics.