  We present a brief overview of the theory of stellar winds with a strong
emphasis on the radiation-driven outflows from massive stars. The resulting
implications for the evolution and fate of massive stars are also discussed.
Furthermore, we relate the effects of mass loss to the angular momentum
evolution, which is particularly relevant for the production of long and soft
gamma-ray bursts. Mass-loss rates are not only a function of the metallicity,
but are also found to depend on temperature, particularly in the region of the
bi-stability jump at 21 000 Kelvin. We highlight the role of the bi-stability
jump for Luminous Blue Variable (LBV) stars, and discuss suggestions that LBVs
might be direct progenitors of supernovae. We emphasize that radiation-driven
wind studies rely heavily on the input opacity data and linelists, and that
these are thus of fundamental importance to both the mass-loss predictions
themselves, as well as to our overall understanding of the lives and deaths of
massive stars.
