UV Spectroscopy of Massive Stars

We present a review of UV observations of massive stars and their analysis. We discuss O stars, luminous blue variables, and Wolf-Rayet stars. Because of their effective temperature, the UV (912-3200 angstrom) provides invaluable diagnostics not available at other wavebands. Enormous progress has been made in interpreting and analysing UV data, but much work remains. To facilitate the review, we provide a brief discussion on the structure of stellar winds, and on the different techniques used to model and interpret UV spectra. We discuss several important results that have arisen from UV studies including weak-wind stars and the importance of clumping and porosity. We also discuss errors in determining wind terminal velocities and mass-loss rates.