https://www.cnet.com/news/galaxy-fold-hands-on-i-just-tried-samsungs-foldable-phone-irl-and-it-was-amazing/

Foldable phones are an insane idea, not because the phone itself bends, but because the screen does, and that's really hard to do and even harder to do well -- I'll eventually let you know if this one does. A few years ago, a foldable phone sounded like a futuristic joke: Oh, sure, you'll just fold up your phone and stick it in your pocket, uh huh. We can't stop our regular glass phone screens from breaking, and now you want to make the screens plastic and bend them? 

But now there's enough critical mass, thanks to phone-makers like Samsung, Huawei and TCL, that foldable phones are becoming more real every day. Even Google's in on the action, pledging Android support so that its software will switch from one screen orientation to another as you fold and unfold the display. A little-known company sold the first foldable phone, the Royole FlexPai, but Samsung's Fold here is the first "real" foldable phone for most people.