Refraction is used for:

Glasses (spectacles) make use of refraction to correct the vision of people who are nearsighted or farsighted.

Telescopes use it to present images of distant objects.

Prisms refract light into discrete colors. This information can be used to determine the chemical content of a distant star or something being burned here on earth.

Refraction is the change in direction of a wave due to a change in its transmission medium.

Refraction is the bending of sound or light waves or the the way of light bends entering the eye. Like when rainbows occur that is a refraction.