We evaluate the place of Eta Carinae ( \eta Car ) amongst the class of luminous blue variables ( LBVs ) and show that the LBV phenomenon is not restricted to extremely luminous objects like \eta Car , but extends luminosities as low as log ( L / \mbox { $L _ { \odot } $ } ) \sim 5.4 – corresponding to initial masses \sim 25 M _ { \odot } , and final masses as low as \sim 10-15 M _ { \odot } .
We present a census of S Doradus variability , and discuss basic LBV properties , their mass-loss behaviour , and whether at maximum light they form pseudo-photospheres .
We argue that those objects that exhibit giant \eta Car-type eruptions are most likely related to the more common type of S Doradus variability .
Alternative atmospheric models as well as sub-photospheric models for the instability are presented , but the true nature of the LBV phenomenon remains as yet elusive .
We end with a discussion on the evolutionary status of LBVs – highlighting recent indications that some LBVs may be in a direct pre-supernova state , in contradiction to the standard paradigm for massive star evolution .