What is refection?

Refraction is the bending of light as it passes from one medium to another, caused by a change in its speed. This phenomenon occurs when light travels through materials with different densities, such as air to water. The degree of bending depends on the angle of incidence and the refractive indices of the involved media. Refraction is responsible for various optical effects, including the apparent bending of a straw in a glass of water.