Connection begins with an HTTP request that includes the Upgrade: websocket header. The server responds with 101 Switching Protocols to establish the WebSocket connection.
Unlike HTTP where connections are closed after each request/response, WebSocket maintains a persistent TCP connection until explicitly closed by either party.
Both client and server can independently send messages at any time without waiting for a request. This enables real-time updates and notifications.
After the initial handshake, WebSocket frames have minimal header information (as little as 2 bytes), making it efficient for frequent small messages.