Abstract
A review is given of experimental data on 
oscillations. Basic theoretical concepts are discussed and an analogy with 
oscillations is noted. A detailed analysis is given of experimental searchesfor oscillations with particular attention devoted to the ARGUS data, which reveal 
mixing with r = Γ(
→ 
→ X')/Γ( → X) = 0.21±0.08. The consequences of large mixing are examined and future studies of the properties of the b quark are discussed.