UV light carries more energy than both visible and infrared light, and therefore, is more dangerous. The sun emits UV light, and thank goodness the ozone layer blocks out the majority of the sun's harmful UV rays. The ozone layer does have some places where it is compromised, as a result, more of the UV rays are hitting the earth's surface.
Regardless of this, chemical engineers have developed sunscreen to protect our skin from UV light, but it doesn't block 100% of the UV light. We did an experiment in class to detect the percentage of UV light a typical 30 SPF sunblock absorbs, using mathematics to support our study. Thanks to Adam for letting us borrow his family's black light since the experiment didn't work through the windows in our classroom!