Geodetic techniques have contributed to significant advances in our understanding of the Earth over the last hundred years. This session, with only invited talks, will review important geodetic discoveries made over the last century and discuss the evolution of geodetic techniques from point measurements and simple models to global satellites and complex, coupled models. Topics will include: plate tectonics, sea level, the geoid, Earth rotation, the terrestrial reference frame, mapping Earth and seafloor topography, solid earth and ocean tides, and time-variable gravity.