Patent attributes
A notification system provides notifications to a user associated with multiple user devices. The notification system selects a user device to receive a notification based on user behavior, such as user interactions with the notification system via the user device or acknowledgments of notifications received from user devices. The notification is sent to the selected user device, and the notification system waits for an acknowledgment from the selected notification system for an acknowledgement delay period. If no acknowledgment is received within the acknowledgment delay period, an additional user device is selected and the notification is sent to the additional user device.