  We provide an updated recommendation for the usage of sets of parton
distribution functions (PDFs) and the assessment of PDF and PDF+$\alpha_s$
uncertainties suitable for applications at the LHC Run II. We review
developments since the previous PDF4LHC recommendation, and discuss and compare
the new generation of PDFs, which include substantial information from
experimental data from the Run I of the LHC. We then propose a new prescription
for the combination of a suitable subset of the available PDF sets, which is
presented in terms of a single combined PDF set. We finally discuss tools which
allow for the delivery of this combined set in terms of optimized sets of
Hessian eigenvectors or Monte Carlo replicas, and their usage, and provide some
examples of their application to LHC phenomenology.
