  A combination is presented of the inclusive deep inelastic cross sections
measured by the H1 and ZEUS Collaborations in neutral and charged current
unpolarised ep scattering at HERA during the period 1994-2000. The data span
six orders of magnitude in negative four-momentum-transfer squared, Q^2, and in
Bjorken x. The combination method used takes the correlations of systematic
uncertainties into account, resulting in an improved accuracy. The combined
data are the sole input in a NLO QCD analysis which determines a new set of
parton distributions, HERAPDF1.0, with small experimental uncertainties. This
set includes an estimate of the model and parametrisation uncertainties of the
fit result.
