Push notifications are messages sent from servers to devices, prompting mobile applications and browsers to engage users with timely information or actions, regardless of whether the app is active. They serve as a vital tool for re-engaging users by delivering updates, alerts, and personalized content, even when users are offline or have closed the app. Companies like FanHub Media, Hearo, and Pocket Gems leverage push notifications to enhance user engagement in sports, telemedicine, and gaming, respectively. While push notifications on iOS and Android platforms have distinct differences in permissions and visibility, web push notifications extend similar capabilities to desktop environments. PubNub's platform simplifies the integration of push notifications by acting as a bridge between applications and service providers like Apple Push Notification service (APNs) and Firebase Cloud Messaging (FCM), allowing developers to manage notifications across multiple device types with a single function call. By combining push notifications with real-time messaging, PubNub offers a comprehensive solution to maintain user engagement and ensure message delivery, even with user settings that might restrict notifications.