When you create an app in the Telerik Platform, you need to choose between hybrid development with Apache Cordova and NativeScript development.
You can read more about them here.
From your question I assume that you are interested in building a Hybrid application (for mobile devices) and have it also available as an web app in web browsers.
In brief, the mobile apps can access device capabilities such as the accelerometer, camera, contacts, and more. If your mobile apps offers the user the usage of native device capabilities, most of them will not run in a web browser.
Other Telerik Platform services like Data/Users/Analytics are also available for usage in a web app as well.
Let me know if you need additional information.
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