  I review recent developments in the study of the low-x partonic content of
protons and nuclei, with a focus on the latter, as one expects possible
deviations from linear QCD evolution to be most pronounced in that case. I give
examples of recent theoretical descriptions of HERA measurements with a focus
on the role of BFKL evolution. I then concentrate on the status and assumptions
of nuclear PDFs and the possibility to use forward particle production at the
LHC as further constraint, in particular measurements of open charm and the
potential of electromagnetic probes.
