Can you explain what a push token is and how it is used in mobile applications?

Push token is a unique identifier that a mobile application receives from the push notification service (for example, APNs for iOS or FCM for Android). This token is used by the server to send targeted push notifications to a specific device.

Example of usage:

1. When the application is first launched, it requests permission to receive notifications.
2. After permission is granted, the application receives a push token from the system.
3. The token is sent to the application's server.
4. The server uses this token to send notifications via the push notification service.

Thus, the push token links a specific device to the notification server, ensuring message delivery.