Refraction is the bending of the path of a wave phenomenon when it crosses the boundary between media with different refractive indexes.
In the case of light, this characteristic of waves is used in . . .
-- the natural cornea and lens of the living eye
-- corrective eyeglasses
-- hand-held magnifying glasses
-- microscopes
-- the objective optical element of refracting telescopes
-- the eyepieces of ANY telescopes
-- cameras (except pinhole and obscura)
-- binoculars
-- movie projectors and slide projectors
-- jewelers' loupes
-- many flashlights
-- experiments where we stand a pencil in a bowl of water and try to explain why the pencil looks like it's bent or broken
