The solid Earth responds to changes in mass loads by deforming visco-elastically. The last ice age, which ended 18,000 years ago, covered various regions in the Northern Hemisphere under ice sheets that were several kilometers thick. The solid Earth yielded under the load and continued its response even so when the continental ice sheets receded. This process is known as glacial isostatic adjustment (GIA) and is an important signal to be represented in Earth system models and in correcting contemporary observations to account for the impact of climate change on surface processes. For example, ice-sheet-wide mass change estimates require a correction for GIA, which is the largest source of uncertainty. In this chapter, we provide a brief history of GIA research, followed by the latest developments. We emphasize various remote sensing techniques that have pushed our ability to estimate the GIA signal with higher accuracy, which could help geophysicists understand Earth’s rheology better. The recent developments in methods that combine various observations and prior knowledge of the spatiotemporal wavelengths of GIA are also highlighted.