Pusher is a cloud-based service that enables developers to add real-time functionality to their applications. It allows for instant communication between servers and clients, making it easier to build features like chat, notifications, and live updates. By using WebSockets and other technologies, Pusher ensures that data is transmitted quickly and efficiently. With Pusher, developers can focus on creating engaging user experiences without worrying about the complexities of real-time data handling. The platform provides various APIs and libraries for different programming languages, making it accessible for a wide range of applications, from web to mobile.