Born-form approximation and full one-loop results for e^+e^- --> W^+W^- --> 4 fermions (+\gamma)

We review the results on representing the differential cross section for W-pair produciton, including W decay and hard-photon bremsstrahlung, in terms of a Born-form approximation of fairly simple analytic form. The result of the Born-form approximation are compared with full-one-loop results. The emphasis is on the energy range of future $e^{+}{e}^{-}$ (or ${\mu }^{+}{\mu }^{-}$) colliders.