  The inclusive production of hadrons through electroweak currents can be
rigorously analysed with short-distance theoretical tools. The associated
observables are insensitive to the involved infrared behaviour of the strong
interaction, allowing for very precise tests of Quantum Chromodynamics. The
theoretical predictions for $\sigma(e^+e^-\to\mathrm{hadrons})$ and the
hadronic decay widths of the $\tau$ lepton and the $Z$, $W$ and Higgs bosons
have reached an impressive accuracy of $\mathcal{O}(\alpha_s^4)$. Precise
experimental measurements of the $Z$ and $\tau$ hadronic widths have made
possible the accurate determination of the strong coupling at two very
different energy scales, providing a highly significant experimental
verification of asymptotic freedom. A detailed discussion of the theoretical
description of these processes and their current phenomenological status is
presented. The most precise determinations of $\alpha_s$ from other sources are
also briefly reviewed and compared with the fully-inclusive results.
