There are a few things that make Trusted Web Activities different from other ways to integrate web content with your app:

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1) Content in a Trusted Web activity is trusted — the app and the site it opens are expected to come from the same developer. (This is verified using Digital Asset Links.)

2) Trusted Web activities come from the web: they’re rendered by the user’s browser, in exactly the same way as a user would see it in their browser except they are run fullscreen. Web content should be accessible and useful in the browser first.

3) Browsers are also updated independent of Android and your app — Chrome, for example, is available back to Android Jelly Bean. That saves on APK size and ensures you can use a modern web runtime. (Note that since Lollipop, WebView has also been updated independent of Android, but there are a significant number of pre-Lollipop Android users.)

4) The host app doesn’t have direct access to web content in a Trusted Web activity or any other kind of web state, like cookies and localStorage. Nevertheless, you can coordinate with the web content by passing data to and from the page in URLs (e.g. through query parameters, custom HTTP headers, and intent URIs.)

5) Transitions between the web and native content are between activities. Each activity (i.e. screen) of your app is either completely provided by the web, or by an Android activity

