A brief review of CP violation in $K$ and $B$ decays is given. While the
observables $\varepsilon$ and Re$(\varepsilon'/\varepsilon)$ describing CP
violation in neutral $K$ decays do not allow a powerful test of the CKM
mechanism of CP violation, rare $K\to\pi\nu\overline{\nu}$ decays and in
particular the $B$-meson system are much more promising in this respect.
After a brief look at the $K$ system, selected aspects of CP-violating
effects in $B$ decays are discussed. It is pointed out that combined
branching ratios for $B\to\pi K$ modes, which have been observed recently
by the CLEO collaboration, may allow to derive stringent constraints on the
CKM angle $\gamma$ that could open a window to new physics.
