  The subject of particle-antiparticle mixing in the neutral B meson systems is
reviewed. The formalism of B0-B0bar mixing is recalled and basic Standard Model
predictions are given, before experimental issues are discussed and the latest
combinations of experimental results on mixing parameters are presented,
including those on mixing-induced CP violation, mass differences, and
decay-width differences. Finally, time-integrated mixing results are used to
improve our knowledge on the fractions of the various b-hadron species produced
in Z decays and at high-energy colliders.
