  Both components of the Standard Model, QCD and the electroweak sector, are
tested in the H1 and ZEUS experiments at HERA. The inclusive ep single and
double differential cross sections for neutral and charged current processes
are measured in the range of four-momentum transfer squared, Q2, between 0.045
and 30000 GeV2, and Bjorken x between 10^{-6} and 0.65. The neutral current
double differential cross section, from which the proton structure function F2
and the longitudinal structure function FL are extracted, is measured at low x
with typically 1% statistical and 2-3% systematic uncertainties. In a next-to-
leading order (NLO) DGLAP QCD analysis using the H1 measurements and the mu p
data of the BCDMS collaboration the strong coupling constant alpha_s and the
gluon momentum distribution are simultaneously determined. A value of alpha_s
(MZ)=0.1150+-0.0017(exp){+0.0009}{-0.0005}(model) is obtained, with an
additional theoretical uncertainty of about +-0.005, mainly due to the
uncertainty of the renormalisation scale. F2c, the charm contribution to F2, is
measured and well described by the boson gluon fusion production mechanism
using the gluon distribution from the NLO QCD analysis. The gluon distribution
and the strong coupling constant alpha_s are also determined from jet
production. For Q2>1000 GeV2, an asymmetry between e+p and e-p neutral current
scattering is observed and the structure function xF3 is extracted. A fit to
the charged current data is used to determine a value for the W boson
propagator mass. All data are found to be in good agreement with Standard Model
predictions.
