Comment by fivestones

In this context, fundamental just means something inherent to the system, like a thing that can’t happen because of the way the system was defined. A boat fundamentally can’t fly, because it wasn’t made in a way that would allow it to fly. This is different from a plane which is restricted from flying because of a no-fly order. There’s no fundamental restriction (the plane was designed to fly, after all) but there is something keeping it from flying. And maybe one plane get special permission to fly despite the no fly order—that’s a carve out. So with iPhones, they are built in such a way as to allow background execution (there is no fundamental restriction) but Apple has made it so they cannot do so, with certain carve outs for things that people will want to be able to do while the app is in the background, like listening to audio or tracking the phone’s movements with gps. So there isn’t a fundamental restriction to background execution, it’s just a rule Apple makes (and then makes some exceptions to). There are other ways you could use the word fundamental, as in something that is important because other things rely on it. But that’s not the way it was being used here. Hope that helps!