Toast messages and web push notifications are crucial for modern user engagement, serving different purposes in application contexts and user re-engagement strategies. Toast messages, appearing briefly within applications, provide immediate feedback without disrupting users' workflows, while web push notifications, delivered at the browser level, aim to re-engage users who have left the site. The guide explores the differences between these notifications, their ideal use cases, and best practices for implementation, emphasizing the importance of choosing the right notification type based on user interaction goals. Courier streamlines notification management across channels, offering a unified API for web push, email, SMS, and in-app notifications, along with pre-built React components for displaying toast messages. Its platform supports cross-platform compatibility, built-in analytics, and a no-code designer to create branded notification templates, allowing for a cohesive and efficient notification strategy.