G-Sync is a proprietary adaptive sync technology developed by Nvidia aimed primarily at eliminating screen tearing and the need for software alternatives such as Vsync.
It is meant to replace common scalers and be easily integrated by monitor manufacturers, who only have to take care of the power delivery circuit board and input connections.
due to its proprietary nature and the fact that it is still being promoted when free alternatives exist, such as the VESA standard Adaptive-Sync which is an optional feature of DisplayPort version 1.2a.
According to Nvidia, fine tuning is still possible given the fact that all notebooks of the same model will have the same LCD panel, variable overdrive will be calculated by shaders running on the GPU, and a form of frame collision avoidance will also be implemented.
[4] At CES 2018 Nvidia announced a line of large gaming monitors built by HP, Asus and Acer with 65-inch panels, 4K, HDR, as well as G-Sync support.