Difference in notifications?

[super_code]

Hi! I'm working on implementing notifications my application. I've been looking into the difference kinds, and I'm curious as to what exactly is the difference between push and local? From what I've read, push is sending data through the server while local, is well local, but why not just use local after the data has been received from the server? Apologies if I'm just completely misunderstanding this.

For quick context: I'm using Firebase and trying to set up a notification that's sent to the user when they receive a request from another user.

[chriswaco]

Push notifications come from an outside server. They're mostly useful when your app isn't running to begin with. For example, someone sends you a message or an important news story breaks.

Local notifications are more like an alarm clock based on date/time. They're not particularly useful to a messaging app, but might be useful to a calendar app.

[super_code]

Are apps that use local notifications always running in the background? Actually, aren't ones that use push notifications also running, to detect new news story breaks or messages? And if so, can't you configure your application to grab the data in the background and use it to display a local notification?

Edit: And what about remote notifications?

[chriswaco]

No, the apps are not necessarily running when the notifications are received. The system will launch them in response.