All radiation is a form of energy, most of which is invisible to the human eye. UV radiation is only one form of radiation and it is measured on a scientific scale called the electromagnetic (EM) spectrum.
Ozone: When an ozone molecule absorbs even low-energy ultraviolet radiation, it splits into an ordinary oxygen molecule and a free oxygen atom.
Melanin: Melanin absorbs the dangerous UV rays that can do serious skin damage. This is the process that gives you a tan. A tan is a sign that your skin is trying to keep UV rays from damaging your skin.