Tau Decays and αs

The evolution of the determination of the strong coupling constant αs from the leptonic branching ratios, the life-time, and the invariant mass distributions of the hadronic final state of the τ lepton over the last two decades is briefly reviewed. The improvements in the latest ALEPH update are described in some detail. Currently this is one of the most precise αs determinations. Together with the other determination at the Z boson mass pole, they constitutes the most accurate test of the asymptotic freedom in QCD.