As we all know, sending and receiving data as soon as some change happens is real-time data transfer. It can be for some changes that occur in that data. The reason for data change could be user itself or some timed event. In normal scenarios, the user changes should accordingly reflect to other users; for example, chatting applications where people send messages to each other. A chatting application is a very small example of real-time data transfer; let's talk about some big examples like games. Games are the major applications where real-time data transfer is required. But as the industry is growing, our daily use applications are also adopting real-time full-duplex data communication. If we see any stock market application, then we can see live data changes happening, which basically is a good example of server push. In this scenario, the server is pushing data, which is a great feature of WebSockets.