Parallax describes the perceived movement of objects when the viewer moves, i.e., objects further away from the viewer seem to move more slowly in relation to the viewer’s position while objects closer to the viewer seem to move more quickly. This process allows people to gauge how far away an object is due to the overlapping (see: stereoscopic) fields of vision of the human eyes. In the same way, parallax is used to simulate the feeling of depth on a two-dimensional surface for use in 3D videos or VR.
