The technology that enables persistent connections in web applications is called WebSockets. This protocol allows for full-duplex communication between the client and server, facilitating real-time interactions. Unlike traditional HTTP requests, which are stateless and require a new connection for each request, WebSockets maintain an open connection, allowing data to flow bidirectionally. This is particularly useful for applications such as chat apps, online gaming, and live content updates, where immediate data exchange is essential for user experience.