Luminous Blue Variables (LBVs) are a class of stars that are very massive, very luminous, and highly unstable. These evolved stars are believed to be the transitional states between high mass main-sequence stars and Wolf-Rayet stars. Their large photometric fluctuations in the visual wavelengths correspond to eruptions -- periods of high mass loss in the form of an opaque stellar wind. The resulting pseudo- photosphere reduces the observed effective temperature and bolometric correction under constant bolometric luminosity. While the mechanism for eruptions is yet undetermined, it is clear that radiation pressure plays an important role in destabilizing the outer layers. Models involving a modified Eddington limit, one in which opacity is a function of temperature and density, are currently the most promising. A greater understanding of LBVs could eventually lead to their use as distance indicators.