Tell me about WebSocket — what is it and have you used this technology in commercial experience?

WebSocket is a communication protocol that provides a bidirectional communication channel between the client and server over a single TCP connection. Unlike traditional HTTP, where the client initiates each request, WebSocket allows the server to send data to the client at any time without an additional request. This is especially useful for real-time applications: chats, online games, stock trading terminals.

In commercial projects, I used WebSocket to implement a chat in a web application, where it was necessary to instantly transmit messages between users without constant polling of the server. This helped reduce load and improve interface responsiveness.