  We present some of the topics covered in two lectures under the same title
that were given at the "Summer School on High Energy Physics at the LHC: New
trends in HEP" in Natal, Brazil. In this contribution we give a brief review on
the application of perturbative QCD to the hard diffractive processes. Some
examples of phenomenology for the diffractive production of $W/Z$, heavy
$Q\bar{Q}$ and quarkonium in hadron-hadron reactions are presented. It is also
discussed the exclusive diffractive processes in $ep$ interactions. They are in
general driven by the gluon content of proton which is strongly subject to
parton saturation effects in the very high energy limit. These saturation
effects are well described within the color dipole formalism. We present some
examples of corresponding phenomenology as the elastic vector meson production
and the DVCS relying on the color dipole approach.
