  Chiral low-energy constants (LECs) carry the information of short-distance
dynamics involving heavier degrees of freedom not present in the chiral
Lagrangian. Our knowledge of the LECs is all-important at phenomenological
level because their relevance in the prediction of hadronic observables at
low-energies and on the other side because they provide hints on the
construction of a dual theory of QCD in the low-energy regime. I review briefly
the status of these important couplings.
