What a progressive web app is
A PWA is a web app built with modern browser capabilities that give it the things we associate with installed software: it can be added to the home screen, launch in its own window without browser chrome, work without a connection and receive push notifications. From the user's side it simply feels like an app; under the hood it is the web.
The defining trait is that it is installed from the browser rather than downloaded from a marketplace. You visit a site, tap 'add to home screen', and it lives on your device like anything else — no store account, no review queue, no multi-hundred-megabyte download.
How install-from-browser and offline work
The technology that makes this possible is the service worker — a JavaScript file that runs in the background, separate from the page. It intercepts network requests and caches the app's essential resources, so the app can open and keep working with no connection, then quietly sync data when the connection returns.
That same background layer powers push notifications and instant repeat loads. A web app manifest supplies the icon, name and display mode so the installed PWA looks and launches like a first-class app rather than a bookmark.
The advantages that actually matter
Three benefits carry most of the value. Speed and offline resilience, because cached assets mean the app is not helpless the moment the signal drops. Access without friction, because installing is a tap from a link — no store gatekeeping, and far less device storage consumed, which matters most on low-end phones.
And cost and reach, because a PWA is one codebase that runs everywhere a modern browser does, typically a fraction of the cost of building and maintaining separate native apps for iOS and Android. For many products, that is the difference between shipping on every platform and shipping on one.
When native still wins
PWAs are not a universal answer. Native apps still lead where a product needs deep operating-system integration, heavy or specialised hardware access, or the discovery and trust signals of a store listing. If the storefront itself is the distribution channel you are counting on, a PWA gives that up by design.
But for a large class of experiences — maps, tools, dashboards, utilities — a PWA delivers the native feel with none of the store friction. A themeable navigation app is a clean example: full turn-by-turn that installs straight from the browser, reskins entirely per theme, and keeps working as you drive, all without an app-store download.