  Numerous channels of the cross section e+e- --> hadrons have been measured by
the BABAR experiment using the ISR method. For the pi+pi-(gamma) and
K+K-(gamma) channels, BABAR has pioneered the method based on the ratio between
the hadronic mass spectra and mu+mu-(gamma). Many systematic uncertainties
cancel in the ratio, hence the precise measured cross sections. These
measurements have been exploited for phenomenological studies, like the
determination of the hadronic contribution to the anomalous magnetic moment of
the muon (g-2)_mu.
