Mat Honan writes about the rising importance of notifications.

Interactive notifications will spur all sorts of new behaviors. (And yes, Android already has interactive notifications, but the ones in iOS 8 look to go beyond what KitKat can do.) Some of these will be simple, like the ability to reply to an email or text message. But they’re powerful in that you can do this without quitting whatever you’re already doing. And this interactivity is not just limited to system apps. Third-party developers can take advantage of this new capability as well, so you could comment on something on Facebook, respond to a tweet, or even check in on Foursquare. But others are going to be radical, stuff we haven’t imagined yet. Once developers begin to really harness what interactive notifications can do in iOS 8—and they will—it’s going to cause one of the most radical changes since third-party apps. With the advent of iOS 8, notifications are the new interface frontier.

We saw of glimpse of such use of notifications on OS X Mavericks. And we will be getting it on iOS 8 across all apps that support it. This will help to increase app engagement. Instead of being irritated by a notification because opening it would bounce you into another app, you can respond to it and continue with whatever you were doing. As Mat mentions, it will bring about a lot of changes to how your apps will want to engage you.

Tie this in with Continuity and the circle is complete. You can reply to SMS messages and answer phone calls from your iPad and Mac. I’ll be able to continue working on my Mac when I get calls or green bubble messages while my phone is across the room.