  We briefly discuss recent research on the spin-averaged parton densities of
the proton, focusing on some aspects relevant to hard processes at the LHC.
Specifically, after recalling the basic framework and the need for higher-order
calculations, we address the evolution equations governing the scale dependence
of the parton distributions and their solution, schemes for initial conditions
and the inclusion of heavy quarks, recent progress on fits to data, and future
high-precision constraints from LHC measurements.
