CP Violation in K and B meson decays, an introduction

Particle physics experiments have established 5 CP-violating observables: Re(εK), Im(εK), Re(εK'), Im(εK'), and A(B0,B0-bar → J/ψK). The five results are very shortly reviewed. They are then discussed with respect to their classification into four types of CP violation (CPV): 1) CPV in meson-anti-meson oscillations, 2) CPV in decays with contribution of strong phases, 3) CPV in decays without contribution of strong phases, 4) CPV in the interference between oscillation and decay. In the neutral K-meson system, type (1) and type (4) are strongly related because of unitarity. (author)