  Hadronic decays of the $\tau$ lepton provide a clean environment to study
hadron dynamics in an energy regime dominated by resonances, with the
interesting information captured in the spectral functions. Recent results from
ALEPH on exclusive channels are presented, with some emphasis on the $\pi \piz$
final state which plays a crucial role for the determination of the hadronic
contribution to the muon anomalous magnetic moment. Inclusive spectral
functions are the basis for QCD analyses, delivering an accurate determination
of the strong coupling constant, quantitative information on nonperturbative
contributions and a measurement of the mass of the strange quark.
