The magnetospheric system is sustained by the Earth's magnetic field and surrounded by the shocked solar wind, i.e., the magnetosheath. It is a very rich and complex system, with different regions and several phenomena occurring that couple these distant regions, from the foreshock in the solar wind down to the ionosphere and the atmosphere. These coupling mechanisms include, but are not limited to, velocity-shear-driven vortex (e.g., Kelvin Helmholtz), plasma waves, turbulence, or magnetic reconnection. Several aspects of these processes occur at kinetic scales, like field-particle interactions, high-frequency waves, magnetic field reconfiguration or plasma heating. However, their effects have implications at the meso- and global scales of the system: magnetospheric storms and substorms, ionospheric currents, jets and outflows, etc. High-resolution in-situ observations made by spacecraft and state of the art kinetic simulations provide usunderstanding of the microphysics, while combination of ground and space measurements, spacecraft conjunctions and numerical fluid approaches help us understanding the implications at larger scales. Three multi-satellite missions are currently sounding the magnetosphere (Cluster, THEMIS, MMS), and combining them allows us to study these processes at different scales. This session welcomes studies on our current understanding of these multi-scale plasma processes, using spacecraft observations, simulations or a combination of them. Studies complemented with multi-point observations from ground or other space missions such as the Van Allen Probes, Arase (ERG) or Geotail for instance are also encouraged.