The refraction of light is used in many kinds of tools.

A magnifying glass is a type of concave lens, which makes objects seem bigger than they actually are.

A microscope contains several lenses that form an objective. Things that placed in the microscope are viewed through the ocular, which is used to focus the image reflected through the objective. Microscopes can be used to see and study things that we cannot distinguish with the naked eye, such as cells and bacteria. 

Lens telescopes also make use of refraction. A lens telescope contains several lenses. A lens telescopes can be used to study stars and planets.