CP Violation in K and B Decays

We review basic aspects of the phenomenology of CP violation in the decays of $K$ and $B$ mesons. In particular we discuss the commonly used classification of CP violation – CP violation in the mass matrix, in the interference of mixing with decay, and in the decay amplitude itself – and the related notions of direct and indirect CP violation. These concepts are illustrated with explicit examples. We also emphasize the highlights of this field including the clean observables $B(K_L\to {\pi }^0\nu \bar{\nu })$ and ${\cal A}_{CP}(B\to J/\Psi K_S)$. The latter quantity serves to demonstrate the general features of large, mixing induced CP violation in $B$ decays.