PWA is basically a mobile optimized (read: responsive) website that caches page content and data (see IndexedDB). Mobile browsers have the option of "installing

PWA is basically a mobile optimized (read: responsive) website that caches page content and data (see IndexedDB). Mobile browsers have the option of "installing" them, basically saving the data and making a shortcut in your app drawer / home screen. There is also support for push notifications but not on iOS. The idea is basically a web page that still functions if you lose connectivity.