The push service lets the app owners Send a push notification to their users. The Push service also lets app owners segment and target devices based on a type and send allows sending notifications to certain segments only.
Push notifications uses the Phonegap Push Plugin (https://github.com/phonegap/phonegap-plugin-push) with FCM (Firebase Cloud Messaging) for Android and iOS push for iOS devices.
For more information on Push, refer to: http://docs.ionic.io/services/push/ .