APNS & FCM Notification

device native push notifications like Apple Push Notification Service (APNS) or Firebase Cloud Messaging (FCM).

APNS and FCM are both push notification services that we can use to send push notifications to user devices. They both have their own set of native APIs and SDKs that we can use to send users push notifications.

APNS/FCM instead route through a connection the OS itself maintains at all times, so they can wake and notify an app that isn’t running at all