Work for every user, regardless of browser choice, because they are built with progressive enhancement as a core tenet.
Fit any form factor, desktop, mobile, tablet, or whatever is next.
Enhanced with service workers to work offline or on low-quality networks.
Use the app-shell model to provide app-style navigation and interactions.
Always up-to-date thanks to the service worker update process.
Served via HTTPS to prevent snooping and ensure content has not been tampered with.
Are identifiable as "applications" thanks to W3C manifests and service worker registration scope allowing search engines to find them.
Make re-engagement easy through features like push notifications.
Allow users to "keep" apps they find most useful on their home screen without the hassle of an app store.
Easily share via URL and not require complex installation.