A letter from the Revolutionary War with lines written in invisible ink. Credit: Wikimedia Commons Last year, the US Central Intelligence Agency released documents detailing recipes for invisible ink ...

People have always wanted to communicate privately. There once was a time when regular ink was secret enough, because not much of the world knew how to read. Then literacy ruined it for everyone, and ...

My finger hovers over an iMessage obscured by a haze of dancing white dots. Before I tap to dissolve the sparkling pixels and reveal the contents of the message, I know it's going to be juicy, or at ...

Invisible Ink is one of the standout features Apple introduced to iMessage back in 2016, part of a suite of message effects designed to make texting feel more expressive. While others like "Slam" and ...