  Data from the HERA collider experiments, H1 and ZEUS, have been fundamental
to the rapid recent development of our understanding of the partonic
composition of the proton and of QCD. This report focuses on inclusive
measurements of neutral and charged current cross sections at HERA, using the
full available data taken to date. The present precision on the proton parton
densities and the further requirements for future measurements at the Tevatron
and LHC are explored. Emphasis is also placed on the region of very low
Bjorken-x and Q^2. In this region, the `confinement' transition takes place
from partons to hadrons as the relevant degrees of freedom and novel or exotic
QCD effects associated with large parton densities are most likely to be
observed. Finally, prospects for the second phase of HERA running are
discussed.
