A person applying the color-changing tattoo, and a color chart for the medical-alerting tattoo. Ali Yetisen et al. Soon, tattoos won’t just show how cool you are — they’ll also show how healthy you ...

Color surrounds us every day, yet many of us rely on only a handful of words to describe it. We say, “I like a soft blue” or “maybe a darker pink,” but without the right terms, it can be tricky to ...