Push notification

A push notification is a short message delivered by the operating system or browser to a device, appearing whether or not the app is open. For lifecycle teams it is the fastest channel for time-sensitive prompts and among the cheapest per message, but it rests on a permission the user can withdraw without telling you. Watch opt-in rate and uninstall rate together: a frequency that lifts short-term clicks often costs installed base, which is much harder to rebuild.