2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/47896We review the historical developments leading to the Cabibbo-Kobayashi-Maskawa (CKM) quark mixing matrix. Present status of the CKM matrix from direct measurements is summarized, giving also the present profile of the unitarity triangle. CP Violation in the $K^0$ - $\bar{K^0}$ complex and in $B$-meson decays are discussed in the context of the CKM matrix.Latex2e, 25 pages, 3 figures (require epsf.sty). Invited article; to be published in `The Particle Century', Institute of Physics Publishing Inc., Bristol and Philadelphia, (1998); Editor: Gordon FraserHigh Energy Physics - Phenomenologytext