Neutrino mass: What has been accomplished,and what do we need to?

It will be explained why the behaviour of atmospheric neutrinos provides compelling, clean evidence for neutrino mass. The fairly strong evidence for mass from the behaviour of solar neutrinos, and the unconfirmed evidence from the LSND experiment, will be discussed as well. Illustrative neutrino mass scenarios suggested by the existing data will be presented. One of these contains a sterile (non-interacting) neutrino, whose naturalness will be considered. Future experiments which need to be done to confirm the present evidence for neutrino mass, to measure the mass and mixing parameters and test the neutrino mass scenarios, and to further probe the nature of neutrinos, will be pointed out.