  Mass loss is a very important aspect of the life of massive stars. After
briefly reviewing its importance, we discuss the impact of the recently
proposed downward revision of mass loss rates due to clumping (difficulty to
form Wolf-Rayet stars and production of critically rotating stars). Although a
small reduction might be allowed, large reduction factors around ten are
disfavoured.
  We then discuss the possibility of significant mass loss at very low
metallicity due to stars reaching break-up velocities and especially due to the
metal enrichment of the surface of the star via rotational and convective
mixing. This significant mass loss may help the first very massive stars avoid
the fate of pair-creation supernova, the chemical signature of which is not
observed in extremely metal poor stars. The chemical composition of the very
low metallicity winds is very similar to that of the most metal poor star known
to date, HE1327-2326 and offer an interesting explanation for the origin of the
metals in this star.
  We also discuss the importance of mass loss in the context of long and soft
gamma-ray bursts and pair-creation supernovae. Finally, we would like to stress
that mass loss in cooler parts of the HR-diagram (luminous blue variable and
yellow and red supergiant stages) are much more uncertain than in the hot part.
More work needs to be done in these areas to better constrain the evolution of
the most massive stars.
