  The production of a Z boson, decaying to two charged leptons, in association
with jets in proton-proton collisions at a centre-of-mass energy of 13 TeV is
measured. Data recorded with the CMS detector at the LHC are used that
correspond to an integrated luminosity of 2.19 fb$^{-1}$. The cross section is
measured as a function of the jet multiplicity and its dependence on the
transverse momentum of the Z boson, the jet kinematic variables (transverse
momentum and rapidity), the scalar sum of the jet momenta, which quantifies the
hadronic activity, and the balance in transverse momentum between the
reconstructed jet recoil and the Z boson. The measurements are compared with
predictions from four different calculations. The first two merge matrix
elements with different parton multiplicities in the final state and parton
showering, one of which includes one-loop corrections. The third is a
fixed-order calculation with next-to-next-to-leading order accuracy for the
process with a Z boson and one parton in the final state. The fourth combines
the fully differential next-to-next-to-leading order calculation with
next-to-next-to-leading logarithm resummation and parton showering.
