Parallax is the apparent shift in the position of an object or point of view when viewed from different locations. In the field of astronomy, this effect is fundamentally used to determine the distance to celestial bodies. By measuring the apparent angular change of an object's position relative to more distant background stars from two widely separated points in space, a measurement of parallax allows for the calculation of the object's distance using geometric and trigonometric principles. Furthermore, the phenomenon is integral to optics and human vision, where the difference in sensory input received from two separate points of observation helps create the perception of depth and three-dimensional space.