Full-duplex real-time communication — chat, live updates, collaborative editing, and Socket.IO.
Five passes over the same idea, each from a different angle. Do them in order, or jump to whichever you need.
WebSockets provide persistent, full-duplex connections between client and server. After the HTTP upgrade handshake, both sides can send messages freely. Use cases: chat, live dashboards, collaborative editing, gaming. Libraries: Socket.IO, ws (Node.js), SignalR (.NET). Consider SSE for server-only push.
