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What is a progressive web app? A progressive web app (PWA) is an app that's built using web platform technologies, but that provides a user experience like that of a platform-specific app. Platform-specific apps are developed for a specific operating system (OS) and/or class of device, like an iOS or Android device, generally using an SDK provided by the platform vendor. They are usually distributed using the vendor's app store, where the user can find and install them, and they subsequently seem to the user like a permanent extra feature of their device, expanding its capabilities in some way. Easy for users to access: They get their own icon on the device, making it easy for users to find and open them. Offline and background operation: They are able to operate when the user is not interacting with them and when the device is offline. This, for example, enables a chat app to receive messages when it is not open, and display a notification to the user.
It also enables a news app to update in the background so it can show fresh content even if the device is offline. Dedicated UI: They can implement their own distinctive, immersive UI. OS integration: They can be integrated into the host OS: for example, a messaging app can register as a share target, enabling users to select an image in the photo app and send it using the messaging app. They can also access device features such as the camera, GPS or accelerometer. App store integration: They are distributed using the app store, giving users a single place to find them and a consistent way to decide whether they want to install them. Traditionally, websites are less like "something the user has" and more like "somewhere the user visits". Typically, a website: does not have a presence on the user's device when the user is not accessing it, can only be accessed by the user opening the browser and navigating to the site, and is highly dependent on network connectivity.
Single codebase: Because the web is inherently cross-platform, a website can run on different operating systems and device classes from a single codebase. Distribution via the web: The web is a great distribution platform. Websites are indexed by search engines, and can be shared and accessed just using URLs. A website can be distributed with no need to sign up to any vendor's app store. Progressive web apps combine the best features of traditional websites and platform-specific apps. PWAs are developed using standard web platform technologies, so they can run on multiple operating systems and device classes from a single codebase. PWAs can be accessed directly from the web. PWAs can be installed on the device. This means: - The PWA can be installed from platform's app store or installed directly from the web. The PWA can be installed like a platform-specific app, and can customize the install process. Once installed, the PWA gets an app icon on the device, alongside platform-specific apps.
Once installed, the PWA can be launched as a standalone app, rather than a website in a browser. Work while the device does not have network connectivity. Update content in the background. Respond to push messages from the server. Display notifications using the OS notifications system. When you visit a website in the browser, it's visually apparent that the website is "running in the browser". The browser UI provides a visible frame around the website, including UI features like back/forward buttons and a title for the page. The Web APIs your website calls are implemented by the browser engine. PWAs typically look like platform-specific apps - they are usually displayed without the browser UI around them - but they are, as a matter of technology, still websites. This means they need a browser engine, like the ones in Chrome or Firefox, to manage and run them. With a platform-specific app, the platform OS manages the app, providing the environment in which it runs.
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