  Moments of the photon energy spectrum in B -> Xs gamma decays, of the
hadronic mass spectrum and of the lepton energy spectrum in B -> Xc l nu decays
are sensitive to the masses of the heavy quarks as well as to the
non-perturbative parameters of the heavy quark expansion. Several measurements
have been performed both at the Upsilon(4S) resonance and at Z0 center of mass
energies. They provide constraints on the non-perturbative parameters, give a
test of the consistency of the theoretical predictions and of the underlying
assumptions and allow to reduce the uncertainties in the extraction of |Vcb|.
