The CKM matrix: from the Standard Model to New Physics

I present the current status of the Cabbibo-Kobayaski-Maskawa matrix describing mixing and CP violation in the quark sector. I review the main ingredients of the standard global analysis, with an emphasis on the recent B-factory results and their theoretical interpretation. I describe the main hints of a tension between the various sources of information. I discuss the role of uncertainties, on the theory side from lattice gauge simulations, and on the experimental side from bias effects. Using the same approach, I consider and constrain a straightforward extensions of the Standard Model from data in flavour physics : the case of New Physics affecting neutral meson mixing only (Delta F=2 processes).