$α_s$ 2002

An update of measurements of the strong coupling constant $\alpha_s$ is given, representing the status of September 2002. The results convincingly prove the energy dependence of $\alpha_s$ and are in excellent agreement with the expectations of Quantum Chromodynamics, QCD. Evolving all results to the rest energy of the $Z^0$ boson, the new world average of $\alpha_s(M_Z)$ is determined from measurements which are based on QCD calculations in complete NNLO perturbation theory, giving $$ \alpha_s(M_Z) = 0.1183 \pm 0.0027 . $$