Weak decays of pseudo Goldstone bosons
  A short overview of recent progress in describing kaon and pion decays within Chiral Perturbation Theory is presented. Particular attention is devoted to the issues of final-state interactions and isospin breaking in $K \to 2 \pi$, as well as to the estimate of long-distance contributions in $K \to \ell^+\ell^- (\pi)$. 
Gino Isidori