WebSocket

WebSocket is the full-duplex communication protocol: it establishes a persistent, low-latency, bidirectional channel over a single TCP connection.

WebSocket fundamentally changes client-server interaction from HTTP's request/response model by delivering persistent, full-duplex data exchange. The connection initiates via an HTTP/1.1 handshake (using the `Upgrade` header), then switches to the dedicated, stateful WebSocket protocol. This single, long-lived TCP connection (often on Port 443 for secure `wss://`) minimizes per-message overhead, eliminating the need for constant polling. The result is a low-latency, real-time data flow: essential for applications like live chat, multiplayer gaming, and financial trading dashboards.

https://websockets.spec.whatwg.org/