  In view of possible photoproduction studies in ultraperipheral heavy-ion
collisions at the LHC, we briefly review the present theoretical understanding
of photons and hard photoproduction processes at HERA, discussing the
production of jets, light and heavy hadrons, quarkonia, and prompt photons. We
address in particular the extraction of the strong coupling constant from
photon structure function and inclusive jet measurements, the infrared safety
and computing time of jet definitions, the sensitivity of dijet cross sections
on the parton densities in the photon, factorization breaking in diffractive
dijet production, the treatment of the heavy-quark mass in charm production,
the relevance of the color-octet mechanism for quarkonium production, and
isolation criteria for prompt photons.
