  I review recent progress on understanding eruptions of unstable massive
stars, with particular attention to the diversity of observed behavior in
extragalatic optical transient sources that are generally associated with giant
eruptions of luminous blue variables (LBVs). These eruptions are thought to
represent key mass loss episodes in the lives of massive stars. I discuss the
possibility of dormant LBVs and implications for the duration of the greater
LBV phase and its role in stellar evolution. These eruptive variables show a
wide range of peak luminosity, decay time, expansion speeds, and progenitor
luminosity, and in some cases they have been observed to suffer multiple
eruptions. This broadens our view of massive star eruptions compared to
prototypical sources like Eta Carinae, and provides important clues for the
nature of the outbursts. I also review and discuss some implications about the
possible physical mechanisms involved, although the cause of the eruptions is
not yet understood.
