This working group deals with single and multiple parton interactions and covers the full range of studies concerning the partonic content of the nucleon and nuclei from an experimental and theoretical points of view. The quantification of the contribution of the orbital angular momentum of quarks and gluons to the spin distribution of nucleons, the origin of the nucleon mass and the pressure inside the latter in terms of partonic constituents are central topics, together with the understanding of multiple parton interactions that impact, at very high collision energy, directly the cross sections and angular distributions measured at the LHC. This working group includes also developments that aim at the study of the contribution of gluons to the properties of hadrons at the future electron-ion collider.
