This tutorial provides a comprehensive guide on how to send Android push notifications from web apps using JavaScript without setting up a dedicated server, by leveraging the PubNub Push APIs alongside PhoneGap. The process involves setting up Google Cloud Messaging (GCM) to receive notifications on Android devices, creating an Android app using Cordova to register devices with GCM, and developing a web interface to send notifications via PubNub's Mobile Push Gateway. The tutorial includes a practical demo where a simulated Internet of Things desktop controller sends push notifications to an Android device when the room temperature exceeds a certain level. It emphasizes the ease of using PubNub to handle server-side tasks and provides simplified code samples for easier understanding, with full source codes available on GitHub for further exploration.