  We review lattice results relevant for pion and kaon physics with the aim of
making them easily accessible to the particle physics community. Specifically,
we review the determination of the light-quark masses, the form factor f_+(0),
relevant for the semileptonic K -> pi transition at zero momentum transfer as
well as the ratio f_K/f_pi of decay constants and discuss the consequences for
the elements V_{us} and V_{ud} of the CKM matrix. Furthermore, we describe the
results obtained on the lattice for some of the low-energy constants of
SU(2)_LxSU(2)_R and SU(3)_LxSU(3)_R Chiral Perturbation Theory and review the
determination of the B_K parameter of neutral kaon mixing. We introduce quality
criteria and use these when forming averages. Although subjective and
imperfect, these criteria may help the reader to judge different aspects of
current lattice computations. Our main results are summarized in section 1.2,
but we stress the importance of the detailed discussion that underlies these
results and constitutes the bulk of the present review.
