[en] The solar-wind magnetosphere interaction process and the coupling between ionosphere and magnetosphere are reviewed. The key-role that is played by the interplanetary magnetic field in the reconnection model of magnetosphere, first shaped by Dungey is discussed and the basic compatibility of the observation with this model is emphasized. The role of wave-particle interaction for stably trapped particles inside the magnetosphere, particle participation in the ionosphere and very low frequency emissions are also discussed. The similarity between the frequency -time structure of VLF emissions and that of solar radio bursts is pointed out. For Jupiter's magnetosphere it is found that energy input from the solar wind could not be neglected even if Jupiter had a radial outflow solution. (author)