What are the advantages and disadvantages of polymorphism?

Short answer: Advantages: Promotes code reuse and flexibility Enables loose coupling Supports extensible architecture Disadvantages: May introduce runtime overhead Can make code harder to understand if overused Requires careful design to avoid ambiguity

Real-world example (ShopNest)

Checkout calls IPaymentGateway.Charge(). Razorpay and Stripe adapters implement the same interface, so ShopNest can switch gateways without rewriting the order service.

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.