WebSocket

A persistent two-way connection between client and server over a single TCP connection — either side can push data to the other at any time without a request.

Example: A live chat app or a collaborative editor where updates appear in real time without polling.

In practice: The right choice when the server needs to push events to the client unprompted — for simpler one-way server push, Server-Sent Events are often enough with less overhead.

• often confused with Webhook