Establishment of CP violation in B decays

Until recently, CP violation had been observed only in kaon decays. In order to conclusively interpret CP violation and test whether it can be explained in the framework of the Cabibbo-Kobayashi-Maskawa matrix, two asymmetric B factories, KEK-B and PEP-II, were constructed in the past decade. Recent measurements with the two detectors at these B factories clearly established large CP violation in neutral B mesons. We review the results and outline the prospects for future measurements.