  I describe recent progress in terms of 3D hydrodynamical model atmospheres
and 3D line formation and their applications to stellar abundance analyses of
late-type stars. Such 3D studies remove the free parameters inherent in
classical 1D investigations (mixing length parameters, macro- and
microturbulence) yet are highly successful in reproducing a large arsenal of
observational constraints such as detailed line shapes and asymmetries. Their
potential for abundance analyses is illustrated by discussing the derived
oxygen abundances in the Sun and in metal-poor stars, where they seem to
resolve long-standing problems as well as significantly alter the inferred
conclusions.
