  We perform a comprehensive new Monte Carlo analysis of high-energy
lepton-lepton, lepton-hadron and hadron-hadron scattering data to
simultaneously determine parton distribution functions (PDFs) in the proton and
parton to hadron fragmentation functions (FFs). The analysis includes all
available semi-inclusive deep-inelastic scattering and single-inclusive $e^+
e^-$ annihilation data for pions, kaons and unidentified charged hadrons, which
allows the flavor dependence of the fragmentation functions to be constrained.
Employing a new multi-step fitting strategy and more flexible parametrizations
for both PDFs and FFs, we assess the impact of different data sets on sea quark
densities, and confirm the previously observed suppression of the strange quark
distribution. The new fit, which we refer to as "JAM20-SIDIS", will allow for
improved studies of universality of parton correlation functions, including
transverse momentum dependent (TMD) distributions, across a wide variety of
process, and the matching of collinear to TMD factorization descriptions.
