Value of alpha_s from deep-inelastic-scattering data

We report the value of $\alpha_{\rm s}$ obtained from QCD analysis of existing data on deep-inelastic scattering of charged leptons off proton and deuterium and estimate its theoretical uncertainties with particular attention paid to impact of the high-twist contribution to the deep-inelastic-scattering structure functions. Taking into account the major uncertainties the value $\alpha^{\rm NNLO}_{\rm s}(M_{\rm Z})=0.1143 \pm 0.0014({\rm exp.})\pm 0.0013({\rm theor.})$ is obtained. An extrapolation of the LO--NLO--NNLO results to the higher orders makes it possible to estimate $\alpha^{\rm N^3LO}_{\rm s}(M_{\rm Z})\sim 0.113$.