  This paper presents cross sections for the production of a W boson in
association with jets, measured in proton--proton collisions at $\sqrt{s}=7$
TeV with the ATLAS experiment at the Large Hadron Collider. With an integrated
luminosity of $4.6 fb^{-1}$, this data set allows for an exploration of a large
kinematic range, including jet production up to a transverse momentum of 1 TeV
and multiplicities up to seven associated jets. The production cross sections
for W bosons are measured in both the electron and muon decay channels.
Differential cross sections for many observables are also presented including
measurements of the jet observables such as the rapidities and the transverse
momenta as well as measurements of event observables such as the scalar sums of
the transverse momenta of the jets. The measurements are compared to numerous
QCD predictions including next-to-leading-order perturbative calculations,
resummation calculations and Monte Carlo generators.
