Refraction refers to the bending of waves as they pass from one medium to another, resulting in a change in their direction and speed. This phenomenon occurs due to the change in the wave's velocity when it encounters a boundary between two media with different refractive indices. The degree of bending depends on the angle of incidence and the refractive indices of the media involved. Refraction is a fundamental concept in optics as it governs the behaviour of light when it passes through lenses, prisms, and other optical devices. It enables the focusing of light, formation of images, and the correction of vision in eyeglasses.