B0-B0bar mixing

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 at high-energy colliders.