Here's a breakdown:

* Light travels at different speeds in different mediums. When light moves from one medium to another (like from air to glass), it changes speed.

* This change in speed causes the light to bend. The angle at which the light bends is determined by the angle of incidence (the angle at which the light hits the surface) and the refractive indices of the two mediums.

Refraction is the reason why objects appear to be in different positions when viewed through water or glass. It's also the principle behind lenses in eyeglasses, telescopes, and cameras.