Push notifications are an essential tool for driving user engagement and retention, with 44% of iOS users and 91% of Android users opting in to receive them. However, with the average U.S. smartphone user receiving 46 push notifications daily, it's crucial to design effective push notification systems that convince users to opt-in, optimize their design for various devices, ensure timely and personal content, create actionable messages, measure performance, and incorporate them into a multichannel communications strategy. By following best practices such as leveraging product and user data, using contextual awareness, and testing different channels, businesses can increase user engagement, retention, and revenue while maintaining a respectful and non-intrusive approach to push notifications.