Refraction is the differential bending of light as it passes through a medium, and it is used in a wide variety of applications throughout industry and the sciences as well as in living bodies. Light refracted through an optical prism spreads out into a spectrum of its constituent colors and allows individual wavelengths to be examined on their own.
Refraction provides scientists with data about the composition and structure of bodies in space. Outside of the laboratory, refracted light is central to the operation of fiber optic cables. By constructing a cable made from differentiated layers of glass, each with its own refractive index, it is possible to send a pulse of light down a cable for a considerable distance. The refractive gradient between layers of glass inside the cable keeps light of the desired wavelength traveling forward along the cable rather than being absorbed or redirected in a way that interrupts the signal.
Optical glass has a refractive index that is used to bend incoming light to form a coherent picture for people with poor eyesight. When the natural lens of the eye, which also refracts light, becomes stiff or develops a shape that interferes with images, a pair of corrective glasses with the right refractive index usually restores normal vision.