The Problem with HTTP
Standard HTTP is a 'request-response' protocol. The client asks for data, the server sends it, and the connection closes. If building a chat app with HTTP, the browser would have to ask the server 'Any new messages?' every 1 second (Polling). This destroys server performance.
The WebSocket Solution
WebSockets keep a persistent, two-way (bidirectional) connection open between the browser and the server. The server can push data to the client at any time without the client asking for it.
When to Use WebSockets
Use them for WhatsApp clones, collaborative tools (like Google Docs), and live sports updates. Do NOT use them for standard blogs or e-commerce stores—stick to REST APIs for those.