  A significant fraction of pp collisions at the LHC will involve (quasi-real)
photon interactions occurring at energies well beyond the electroweak energy
scale. Hence, the LHC can to some extend be considered as a high-energy
photon-photon or photon-proton collider. This offers a unique possibility for
novel and complementary research where the available effective luminosity is
small, relative to parton-parton interactions, but it is compensated by better
known initial conditions and usually simpler final states. This is in a way a
method for approaching some of the issues to be addressed by the future lepton
collider. Such studies of photon interactions are possible at the LHC, thanks
to the striking experimental signatures of events involving photon exchanges,
in particular the presence of very forward scattered protons.
