Basically, you're sending each other text messages while also watching each other type and send those very text messages. So you can emote with your face while you type with your thumbs, as if you were on either side of a soundproof partition in jail, but the little phone you're supposed to talk on wasn't working, but you both had, say iPod touches to text each other, but you couldn't just Skype or FaceTime or Snapchat or Facebook Messenger or Hangout or Line or WeChat or whatever the kids are doing these days.
"Every platform shift leads to new forms of communication, driven by our desire to connect and interact in richer ways," said Adam Cahan, Senior Vice President of Video, Design, and Emerging Products, in a press release. "We wanted to create a new way to communicate, blending the simplicity of texting with the emotion and immediacy of live video, to make your experience spontaneous and real."
I think that means that Yahoo thinks live but soundless video with subtitles you type yourself is a feature.
The app launches in the App Store and Google Play Store on July 30 in the U.S., U.K., Canada, Germany, and France. It's already available in Hong Kong, Taiwan, and Ireland.