  Rare Kaon decays provide sensitive probes of short distance physics. Among
the most promising modes are the K+ --> pi+ nu anti-nu and K(L) --> pi0 nu
anti-nu modes due to their theoretical cleanness and the dedicated experiments,
NA62 and KOTO. The key to the success of New Physics searches in these modes is
the precision in the standard model prediction. We review the status and the
recent progress of their standard model prediction, and also discuss the
predictions and New Physics sensitivities of the K(L) --> pi0 l+ l- and K(L)
--> mu+ mu- decays.
