  Precise nuclear reaction rates are needed for a detailed description of the
production of elements in primordial nucleosynthesis and during the hydrostatic
burning of stars to constrain the astrophysical models. The relevant reactions
are extremely difficult to measure directly in the laboratory at the small
astrophysical energies. In recent years direct reactions methods have been
developed and applied to extract low-energy astrophysical S factors. The
application of these methods requires a combination of experimental and
theoretical efforts. This contribution focuses on the underlying reaction
theories that have to be well understood in order to assess the precision and
limitations of the various approaches.
