  The current status of the experimental knowledge of neutral B meson
oscillation is reviewed. The B0d oscillation frequency is precisely measured by
SLD, CDF and the LEP experiments. An overview of the analyses and their
combination is presented. Preliminary measurements and perspectives at the
running B factories are also briefly discussed. The much faster B0s
oscillations have not yet been resolved, despite the progress recently by SLD
and ALEPH. The world combination is presented, together with the expected and
observed lower limit on the B0s oscillation frequency. The "amplitude method",
used to combine the analyses in order to set the limits, is discussed also as a
tool to establish the significance of a possible signal.
