I think it's been well answered, but I feel it's a meaningful technology if web apps are to be a real consideration. There's an over-reliance on email being a n

I think it's been well answered, but I feel it's a meaningful technology if web apps are to be a real consideration. There's an over-reliance on email being a notification tool, with plenty of examples such as social media sites which utterly abuse it. The difference for me is straightforward: Email is for messages the user might want to keep, notifications are messages that the user doesn't need to keep. (To extend this further, messaging systems aren't for notifications either, but rather for interactive dialogue.)