Give two product features that need WebSockets instead of polling.

WebSocket use cases

For Give two product features that need WebSockets instead of polling., interviewers listen for a crisp definition, how the pieces interact in a real system, and one trade-off or failure mode you have seen or would guard against.

• Live chat — bidirectional low-latency messages.
• Collaborative editing — cursor positions, doc ops.
• Contrast with polling (wasteful) and SSE (server→client only).