Our understanding of how stars and populations of stars evolve are mostly based on models that assume constant mass.  However, we also know that most stars lose a considerable portion of their masses; for example, our Sun will end up as at 0.5 to 0.6 solar mass white dwarf.  When and how do stars lose this mass, and how do we know?  Are widely used "empirical" mass loss formulae reliable - and if so, why are they so varied in their prescriptions?   I will review what we know from observations about mass loss from stars, and describe what we have learned recently about the mechanism(s) of mass loss for stars like the Sun when they grow old.