A review of the double asymptotic scaling phenomenon for the structure functions of the deep-inelastic scattering process is presented as well as an analytical parameterization of the contributions from the twist-two operators of the Wilson operator product expansion and power suppressed terms. Higher-twist corrections to F₂ at small x are studied for the case of a flat initial condition for the twist-two QCD evolution in the next-to-leading order approximation. Higher-twist terms are estimated using two different approaches - one motivated by BFKL and the other motivated by the renormalon formalism. The results of the latter approach are in very good agreement with deep-inelastic scattering data from HERA.

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