The article shows step by step how to add and run a sample BackgroundTask in your solution. The presented steps are the same for Windows Runtime, Windows Phone 8.1 Silverlight and Windows Phone 8.1 Runtime. As an example the task is run upon a TimeTrigger and sends simple Toast message from the background.
The post is about capturing a photo on WinRT devices (of course those with camera). The presented method uses MediaCapture class. Althought it was tested on Windows Phone 8.1 Runtime, it should also work fine on other devices.
The article shows that some events are run as asynchronous even if you may not be aware of that. This can result in weird behaviour of the App - even hanging it. Simple example of such a behaviour is presented with full code sample. While writing the code in VS, the events aren't marked as asyc - so that is why you may not be aware of that. It is always worth to take a look into documentation.