Glossary

PWA (Progressive Web App)

PWA (Progressive Web App) is a web application that uses modern browser APIs to achieve a native-like experience: install to home screen, offline operation, push notifications. One codebase instead of an iOS app, Android app, and website.

Three pillars of PWA

Service Worker — a JavaScript file that intercepts network requests and enables resource caching for offline use
Web App Manifest — a JSON file with the app name, icons, and display settings: fullscreen mode, theme colour
HTTPS — mandatory; otherwise the Service Worker will not register

Limitations

iOS Safari has limited Service Worker support. Access to hardware features (Bluetooth, NFC) requires native apps. A PWA is not published in the App Store directly (though an iOS PWA wrapper via the App Store is possible).