The ability to glow is a mesmerizing trait – but some things can only do so under certain circumstances, for example, having a black light shone on them. So what is a black light, and how do they work ...

These light-emitting devices are all over the internet. We asked experts if they can reduce wrinkles, clear acne and more. By Melinda Wenner Moyer You’ve probably noticed this scene on social media: ...