Nonzero neutrino masses are the first definitive need to extend the standard
model. After reviewing the basic framework, I describe the status of some of
the major issues, including tests of the basic framework of neutrino masses and
mixings; the question of Majorana vs. Dirac; the spectrum, mixings, and number
of neutrinos; models, with special emphasis on constraints from typical
superstring constructions (which are not consistent with popular bottom-up
assumptions); and other implications.Comment: 13 pages, 6 figures, invited plenary talk at ICHEP200