Android applications, running on either Android itself or on Chrome OS, pause whenever they’re not in focus. While this makes sense on a phone, this doesn’t make a whole lot of sense on desktop machines such as Chromebooks. As such, Google is addressing this shortcoming with Parallel Tasks.
With that in mind, the expected behavior of an open app is that it would remain active and running even when the user clicks to another window. Coming from Windows, Linux, or Mac OS, this is what users expect and it is a bit confusing unless you understand what is happening.
Parallel tasks on Android allow the OS to keep everything running and open until you pause the activity or close the app down. Again, with Chrome OS, this is much easier to manage. Just click the “X” on the app and it is closed. Simple.
Nothing groundbreaking in and of itself, obviously, but a hugely important ‘feature’ to have on a laptop or desktop.