The phenomenon of light bending when it passes from one medium to another is called refraction. Refraction occurs due to a change in the speed of light as it travels through different materials, such as air, water, or glass. This change in speed causes light rays to change direction, resulting in effects such as the bending of a straw appearing broken when placed in a glass of water. Refraction is fundamental to the functioning of lenses, prisms, and optical instruments, shaping our understanding of light behavior and playing a crucial role in various applications in science and technology.