In recent years exciting experimental discoveries have shown that neutrino flavors oscillate, and hence that neutrinos have nonzero masses and mixings. The Standard Model needs to be modified to accommodate neutrino mass terms, which require either the existence of right-handed neutrinos to create Dirac mass terms, and/or a violation of lepton number conservation to create Majorana mass terms. The observation that neutrino masses and mass-splittings are tiny compared to the masses of any of the other fundamental fermions suggests radically new physics, which perhaps originates at the GUT or Planck Scale, or perhaps indicates the existence of new spatial dimensions. Whatever the origin of the observed neutrino masses and mixings is, it will certainly require a profound extension to our picture of the physical world. The first step towards understanding this new physics is to pin down the measurable parameters, and address the first round of basic questions: (1) Are there only three neutrino flavors, or do light sterile neutrinos exist? Are there any other deviations to three-flavor mixing? (2) There is one angle {theta}{sub 13} in the mixing matrix which is unmeasured. Is it non-zero? (3) We don't know the mass-ordering of the neutrino mass eigenstates. There are two possibilities, the so-called ''normal'' or ''inverted'' hierarchies. Which is right? (4) There is one complex phase {delta} in the mixing matrix which is accessible to neutrino oscillation measurements. If both {theta}{sub 13} and sin {delta} are non-zero there will be CP Violation in the lepton sector. Is sin {delta} non-zero? (5) What precisely is the value of the lightest neutrino mass and are neutrino masses generated by Majorana mass terms, Dirac mass terms, or both? All of these questions, with the exception of the last one, can in principle be addressed by accelerator-based neutrino oscillation experiments. However, getting all of the answers will not be easy, and will require the right experimental tools. A Neutrino Factory appears to be the ultimate tool for probing appears to be the ultimate tool for probing neutrino oscillations. Hence the interest in this new type of neutrino source
