Here's a breakdown:

* Refraction is the bending of light (or any wave) as it passes from one medium to another. This happens because the speed of light changes as it enters a new medium with a different refractive index.

* Refractive index is a measure of how much light slows down when it enters a material. A higher refractive index means light travels slower in that material.

* Wavelength is the distance between two successive crests or troughs of a wave. When light slows down, its wavelength also decreases.

So, when light enters a new material, its speed and wavelength change, causing it to bend or refract.