The last two decades brought a rich harvest of information about the outer planets, their satellites, and their ring systems that dramatically improved our knowledge about these bodies and evolutionary processes in the Solar System. This progress was due both to the successful Pioneer and Voyager missions, and to progressively improved techniques of ground-based observations. These data give insight into numerous new phenomena and mechanisms operating on the outer planets and also give important clues about the intimate relationships between all objects of the Solar System family. Results from the Galileo probe and orbiter have taken us further along that track.