How does REST ensure scalability and flexibility in API design?

Short answer: Statelessness → No server memory required for client sessions → Easy to scale horizontally. Layered System → Load balancers, caching layers can be added without changing API. Uniform Interface → Predictable, decouples client and server. Cacheability → Reduces server load.

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.