A review is given of experimental data on $\mathrm{B^0\bar B^0}$ oscillations. Basic theoretical concepts are discussed and an analogy with $\mathrm{K^0\bar K^0}$ oscillations is noted. A detailed analysis is given of experimental searchesfor $\mathrm{B^0\bar B^0}$ oscillations with particular attention devoted to the ARGUS data, which reveal $\mathrm{B^0_d\bar B^0_d}$ mixing with $r=\Gamma(\mathrm{B^0}\to\bar{\mathrm B}^0$ $\to X'$)/$\Gamma$($\mathrm{B^0}$ $\to X$) = 0.21 $\pm$ 0.08. The consequences of large $\mathrm{B^0\bar B^0}$ mixing are examined and future studies of the properties of the b quark are discussed.