What is rate limiting, and why is it important for REST APIs?

Short answer: Rate limiting restricts the number of API requests per user/IP in a given time. Prevents abuse (DDoS, brute force). Ensures fair usage and protects backend systems. Return 429 Too Many Requests with Retry-After header. 👉 Example: 100 requests/minute per API key.

Real-world example (ShopNest)

Creating an order is POST /api/orders → 201 with Location header. Fetching is GET /api/orders/{id} → 200 or 404.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.