What is the Liskov Substitution Principle and how does inheritance affect it?

Short answer: Derived classes should be replaceable by base class without affecting correctness. Inheritance violating this principle can cause unexpected behavior.

Real-world example (ShopNest)

ShopNest has a base PaymentMethod with virtual decimal Fee(). UpiPayment and CardPayment override the fee logic without changing the checkout caller.

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.