  The chemical composition of the Sun is among the most important quantities in
astrophysics. Solar abundances are needed for modelling stellar atmospheres,
stellar structure and evolution, population synthesis, and galaxies as a whole.
The solar abundance problem refers to the conflict of observed data from
helioseismology and the predictions made by stellar interior models for the
Sun, if these models use the newest solar chemical composition obtained with 3D
and NLTE models of radiative transfer. Here we take a close look at the problem
from observational and theoretical perspective. We also provide a list of
possible solutions, which have yet to be tested.
