It is the aim of this talk to review our understanding of the high-energy
limit of QCD, focussing, in particular, on recent theoretical developments.
After a brief introduction, I will recall why the true high-energy limit of QCD
scattering processes is genuinly non-perturbative and why it has so far not
been possible to apply lattice methods to this type of physics. Given the
experimental fact of slowly rising hadronic cross sections, we are thus faced
with a fundamental problem comparable to that of confinement but without the
promise of the lattice. During the last years, the experimental side of this
field has largely been driven by the HERA accelerator, which has, naturally,
also influenced recent theoretical work in high-energy QCD. I will therefore
devote the second part of the talk to small-x deep inelastic scattering, in
particular the physics of diffraction, and attempt to describe its impact on
the wider field of non-perturbative high-energy QCD.Comment: 20 pages LaTeX, 10 figures, Plenary talk at the International
Europhysics Conference on High Energy Physics (EPS HEP 2001), Budapest, 12-18
July 2001, reference adde
