Abstract In this introduction we present a brief status of neutrino mass. As to the importance of this issue, we remind the reader that if finite neutrino mass were established this would constitute clear evidence for new physics beyond the standard model. Included in this review are dynamic tests based on the 3H decay, searches for neutrino decays, searches for heavy neutrinos, and the study of neutrino oscillations. The last three studies also test neutrino mixing, in addition to neutrino mass. Double beta decay, a sensitive probe for Majorana neutrinos, will be covered in the forthcoming lecture by E. Takasugi. For a detailed review we refer the reader to reference 1.