Push notifications are messages that pop up on a customer's phone without opening an app. To be effective, push notifications should build trust with customers by demonstrating value and familiarizing them with the brand. Notifications should be segmented based on audience demographics and purchase history to increase click rates. Messages should remind customers about events and offers while making unsubscribing easy. Results should be measured using tools to track audience response and notification performance over time. Push notifications work best when used strategically and not in excess.