  Birnbaum and Saunders introduced a two-parameter lifetime distribution to
model fatigue life of a metal, subject to cyclic stress. Since then, extensive
work has been done on this model providing different interpretations,
constructions, generalizations, inferential methods, and extensions to
bivariate, multivariate and matrix-variate cases. More than two hundred papers
and one research monograph have already appeared describing all these aspects
and developments. In this paper, we provide a detailed review of all these
developments and at the same time indicate several open problems that could be
considered for further research.
