The phenomenon that describes the bending of light as it passes through different mediums is called refraction. Refraction occurs when light travels from one medium to another with a different density, causing the light to change speed and direction. This principle explains various phenomena, including the formation of rainbows and the way lenses focus light. Refraction is also crucial in many optical devices like glasses, cameras, and other imaging systems, where it aids in accurately capturing and manipulating light.